U.S. patent application number 13/757559 was filed with the patent office on 2013-06-13 for systems, devices, and methods for providing foot loading feedback to patients and physicians during a period of partial weight bearing.
The applicant listed for this patent is Robert W. Hitchcock, Erik N. Kubiak, Kylee North, Tomasz Petelenz. Invention is credited to Robert W. Hitchcock, Erik N. Kubiak, Kylee North, Tomasz Petelenz.
Application Number | 20130150755 13/757559 |
Document ID | / |
Family ID | 48572648 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130150755 |
Kind Code |
A1 |
Kubiak; Erik N. ; et
al. |
June 13, 2013 |
SYSTEMS, DEVICES, AND METHODS FOR PROVIDING FOOT LOADING FEEDBACK
TO PATIENTS AND PHYSICIANS DURING A PERIOD OF PARTIAL WEIGHT
BEARING
Abstract
Systems, devices, and methods for providing user feedback
regarding compliance with a set of partial weight bearing (PWB)
criteria are described. A computer system receives force data from
a non-compressible force transmitter that is assigned to a user,
and accesses the force data received from the non-compressible
force transmitter to determine whether the user is within a
predefined pressure compliance range. The pressure compliance range
specifies a prescribed range of pressure that is to be applied
during a PWB period. The computer system then receives a compliance
data request from the user or the user's physician and communicates
compliance data representing the user's compliance with the
prescribed range of pressure during the PWB period to the user
and/or the user's physician.
Inventors: |
Kubiak; Erik N.; (Salt Lake
City, UT) ; North; Kylee; (Bountiful, UT) ;
Petelenz; Tomasz; (Salt Lake City, UT) ; Hitchcock;
Robert W.; (Sandy, UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kubiak; Erik N.
North; Kylee
Petelenz; Tomasz
Hitchcock; Robert W. |
Salt Lake City
Bountiful
Salt Lake City
Sandy |
UT
UT
UT
UT |
US
US
US
US |
|
|
Family ID: |
48572648 |
Appl. No.: |
13/757559 |
Filed: |
February 1, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13178314 |
Jul 7, 2011 |
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13757559 |
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12833214 |
Jul 9, 2010 |
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13178314 |
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61632879 |
Feb 1, 2012 |
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61617204 |
Mar 29, 2012 |
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Current U.S.
Class: |
600/592 |
Current CPC
Class: |
A61B 5/11 20130101; A61B
5/746 20130101; A61B 5/7275 20130101; A61B 2562/0247 20130101; A61B
5/486 20130101; A61B 5/4833 20130101; A61B 5/6807 20130101; A61B
5/743 20130101; A61B 2562/0252 20130101; A61B 5/1038 20130101; A61B
5/742 20130101; A61B 5/7475 20130101; A61B 5/1036 20130101; A61B
5/0002 20130101; A61B 5/6829 20130101 |
Class at
Publication: |
600/592 |
International
Class: |
A61B 5/103 20060101
A61B005/103; A61B 5/11 20060101 A61B005/11; A61B 5/00 20060101
A61B005/00 |
Claims
1. A system for providing user feedback regarding compliance with a
set of partial weight bearing (PWB) criteria including a weight
range and a prescribed number of steps, the system including: a
receiving module that receives force data from a non-compressible
force transmitter that is assigned to a user; a processing module
that accesses the force data received from the non-compressible
force transmitter to determine whether the user is within a
predefined pressure compliance range, the pressure compliance range
specifying a prescribed range of pressure that is to be applied
during a PWB period; and a communications module that, upon
receiving a compliance data request, communicates compliance data
representing the user's compliance with the prescribed range of
pressure during the PWB period to at least one of the user and the
user's physician.
2. The system of claim 1, wherein the non-compressible force
transmitter is positioned within a cavity of a housing oriented on
the plantar surface of the user's foot.
3. The system of claim 2, wherein the non-compressible force
transmitter is further positioned adjacent to a pressure sensor to
transmit pressure within the housing.
4. The system of claim 3, wherein the pressure sensor is configured
to monitor a load profile of the user during a PWB period, said
pressure sensor being located at least partially within said
cavity.
5. The system of claim 3, wherein the non-compressible force
transmitter further includes an accelerometer that monitors limb
acceleration.
6. The system of claim 1, wherein the wireless communications
module communicates at least one of raw and processed compliance
data to at least one of the user and the user's physician in
response to the compliance data request.
7. The system of claim 6, wherein the raw compliance data is
displayed in a graphical user interface (GUI) that includes a chart
showing the user's compliance over a specified period of time.
8. The system of claim 7, wherein the chart shows the user's level
of compliance with the predefined compliance range over a specified
period of time.
9. The system of claim 1, further comprising a tracking module that
tracks the number of times the user views his or her compliance
data.
10. The system of claim 9, wherein the tracking module tracks the
number of times each graphical display is viewed by the user.
11. The system of claim 1, wherein the compliance data sent to the
user's physician allows the user's physician to make informed
decisions regarding the user.
12. The system of claim 1, wherein the compliance range is
customizable for each user.
13. The system of claim 1, wherein the user's compliance is
determined at a specified periodic rate.
14. The system of claim 12, wherein the specified periodic rate is
provided by the user's physician.
15. The system of claim 1, wherein the compliance data representing
the user's compliance with the predefined compliance range is
automatically synchronized to the user's medical records.
16. The system of claim 1, wherein the user's physician is
automatically alerted if the user is outside of the predefined
compliance range by a specified threshold amount.
17. At a computer system including at least one processor and a
memory, a computer-implemented method for providing user feedback
regarding compliance with a set of partial weight bearing (PWB)
criteria, the method comprising: an act of receiving force data
from a non-compressible force transmitter that is assigned to a
user; an act of accessing the force data received from the
non-compressible force transmitter to determine whether the user is
within a predefined pressure compliance range, the pressure
compliance range specifying a prescribed range of pressure that is
to be applied during a PWB period; an act of receiving a compliance
data request from at least one of the user and the user's
physician; and an act of communicating compliance data representing
the user's compliance with the prescribed range of pressure during
the PWB period to at least one of the user and the user's
physician.
18. The computer-implemented method of claim 17, further comprising
an act of dynamically generating a graphical user interface (GUI)
that displays at least a portion of the accessed compliance
data.
19. The computer-implemented method of claim 17, further comprising
an act of receiving from the user's physician a compliance
prescription indicating an updated compliance range based on the
user's activity.
20. A computer system comprising the following: one or more
processors; system memory; one or more computer-readable storage
media having stored thereon computer-executable instructions that,
when executed by the one or more processors, causes the computing
system to perform a method for gathering and storing force data to
determine users' compliance with a predefined pressure compliance
range, the method comprising the following: an act of receiving an
indication that a period of partial weight bearing (PWB) has been
initiated for a user; an act of initiating a non-compressible force
transmitter that is assigned to the user, the non-compressible
force transmitter being positioned both within a cavity of a
housing oriented with respect to the user's leg and adjacent to a
pressure sensor to transmit pressure within the housing; an act of
storing, at specified intervals, one or more portions of force data
sensed by the pressure sensor, the force data indicating the user's
compliance with a prescribed range of pressure that is to be
applied during the PWB period; and upon receiving a request for
stored force data, an act of sending the stored force data to the
data requester.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of, and claims
the benefit of and priority to, U.S. patent application Ser. No.
13/178,314, filed on Jul. 7, 2011, and entitled "SYSTEMS, DEVICES,
AND METHODS FOR MONITORING AN UNDER FOOT LOAD PROFILE OF A PATIENT
DURING A PERIOD OF PARTIAL WEIGHT BEARING", which itself is a
continuation-in-part of, and claims the benefit of and priority to,
U.S. patent application Ser. No. 12/833,214, filed on Jul. 9, 2010,
and entitled "SYSTEMS, DEVICES, AND METHODS FOR MONITORING AN UNDER
FOOT LOAD PROFILE OF A TIBIAL FRACTURE PATIENT DURING A PERIOD OF
PARTIAL WEIGHT BEARING", which applications are both hereby
expressly incorporated herein by reference in their entirety.
[0002] This application also claims priority to and the benefit of
U.S. Provisional Patent Application Ser. No. 61/632,879, filed on
Feb. 1, 2012, entitled "EFFECTS OF KNEE-HIGH WALKING BOOT CASTS ON
PEAK PLANTAR LOADS", and U.S. Provisional Patent Application Ser.
No. 61/617,204, filed on Mar. 29, 2012, entitled "SYSTEMS, DEVICES,
AND METHODS FOR PROVIDING FOOT LOADING FEEDBACK TO PATIENTS AND
PHYSICIANS DURING A PERIOD OF PARTIAL WEIGHT BEARING", which
applications are both hereby expressly incorporated herein by
reference in their entirety.
BACKGROUND
[0003] 1. The Field of the Disclosure
[0004] The present disclosure relates generally to systems,
devices, and methods for measuring under foot load profiles. More
particularly, the disclosure relates to systems, devices, and
methods for monitoring an under foot load profile of a patient
during a period of partial weight bearing (PWB).
[0005] 2. The Relevant Technology
[0006] Bone fractures, or broken bones, may be caused by direct or
indirect forces to a bone, or as a result of certain medical
conditions, such as osteoporosis. Falls, sports injuries, and motor
vehicle accidents are common causes of fractures. Fractures can be
very painful, can take significant time to heal, and can result in
significant costs.
[0007] For instance, the tibia, which is the most commonly broken
long bone in the body, typically requires between about ten weeks
and about ten months to heal completely. By some estimates, the
number and severity of complications associated with tibial
fractures results in an annual direct cost for the United States of
about $1.2 billion USD. When indirect costs such as lost wages are
factored, in the long rehabilitation period for tibial fracture
patients results in an estimated annual indirect cost of about $95
billion USD.
[0008] The mechanical environment experienced by the recovering
bone is a major factor in fracture healing rate. In an attempt to
produce an optimal mechanical environment that promotes bone
healing while reducing risk of complications, clinicians routinely
prescribe PWB during fracture rehabilitation. For example, PWB is
commonly prescribed during rehabilitation of hip and lower
extremity injuries, such as fractures to hips, femurs, tibias,
ankles, calcanei, metatarsals, and the like.
[0009] The PWB prescription for a patient varies based on the type
and extent of the injury and on the discretion of the clinician.
Unfortunately, little data has been collected to support a
conclusion that PWB prescriptions are effective at either promoting
fracture healing or reducing the risk of complications.
Additionally, the patients' tendencies or abilities to comply with
the PWB prescription for the entire duration between follow-up
visits are unknown. Therefore, clinicians and researchers would
greatly benefit from a load monitoring device that can continually
track the PWB behavior of a patient between follow-up visits. As
follow-up visits may be scheduled one day, a week, or even
two-weeks apart, clinicians and researches would greatly benefit
from a robust monitoring device capable of tracking the PWB
behavior even over extended periods of time.
[0010] The subject matter claimed herein is not limited to
embodiments that solve any disadvantages or that operate only in
environments such as those described. Rather, this background is
only provided to illustrate one exemplary technology area where
some embodiments described herein may be practiced.
BRIEF SUMMARY
[0011] The present disclosure relates generally to systems,
devices, and methods for measuring under foot load profiles. More
particularly, the disclosure relates to systems, devices, and
methods for monitoring an under foot load profile of a fracture
patient during a period of partial weight bearing (PWB).
[0012] An embodiment of the present disclosure relates to a system
for measuring an under foot load profile of a fracture patient
during a period of PWB, and includes a housing, pressure sensor,
and non-compressible force transmitter. The housing may be oriented
with respect to a patient's fractured bone and defines a cavity.
The pressure sensor is configured to monitor the load profile of
the fracture patient during the desired period of PWB, and the
pressure sensor is located at least partially within the cavity. A
non-compressible force transmitter within the cavity is adjacent
the pressure sensor so as to transmit pressure within the
housing.
[0013] In some embodiments, the pressure sensor is fully
encapsulated within the non-compressible force transmitter.
Moreover, the pressure sensor may include a piezoresistive
Wheatstone bridge pressure sensor or other similarly capable
sensor. The non-compressible force transmitter may be silicone gel
or another silicone-based composition.
[0014] According to some embodiments of the present disclosure, a
movable piston is connected to a non-compressible force
transmitter. A piston may, for instance, include a surface that is
movable relative to the housing, and such movement can correspond
to a pressure applied to, or transmitted from, a pressure sensor.
In at least some embodiments, a lower-leg immobilizer such as a
walking boot cast is included with the system. When the system
includes a lower-leg immobilizer, the housing may be at least
partially located in a heel or ball region of the lower-leg
immobilizer. The housing may also be placed at other locations
along the plantar surface. In some other embodiments, the housing
may be incorporated into any lower leg orthosis other than a
walking boot cast, such as any ankle foot orthosis, a hard or other
cast, a camwalker, hard sole shoes, cast shoes, or a patient's
regular footwear. For instance, the housing may be configured as an
insole insert that may be selectively placed in various types of
footwear.
[0015] In some cases, the pressure sensor is located within a lower
portion of the cavity of the housing, and optionally at least
proximate a lower internal surface of the housing. The pressure
sensor can be positioned relative to the non-compressible force
transmitter so as to receive a pressure applied to the housing from
the non-compressible force transmitter. The pressure sensor may
also transmit a received pressure to an inner contact surface of
the housing, although the pressure sensor may additionally or
alternatively transmit a received pressure to the non-compressible
force transmitter.
[0016] In operation, a housing may define an aperture in at least a
portion thereof. For instance, the aperture may provide a reference
pressure for determining a load profile. A reference pressure may
include an absolute pressure, and a load profile can be determined
as a relative pressure differential. A storage device is optionally
included in the device. A storage device may be configured to
receive a measure of a load profile from the pressure sensor. The
storage device may be integral with, local to, or remote from the
pressure sensor. In some cases, an aperture in the housing is used
for a communication device that couples the pressure sensor to the
storage device. In still other embodiments, the pressure sensor is
configured for wireless communication with the storage device.
[0017] During a period of PWB, the pressure sensor potentially
provides continuous monitoring and/or transmission of the load
profile to the storage device. Such monitoring may be over the full
period of PWB, and can be periodic or continuous. For instance, the
pressure sensor may continuously obtain substantially uninterrupted
results over the full period of PWB. The pressure sensor may
alternatively obtain periodic results over the full period of
PWB.
[0018] In accordance with another example embodiment, a method is
performed for measuring an under foot load profile of a bone
fracture patient during a period of PWB. In at least some aspects,
a method may include substantially immobilizing a bone of a bone
fracture patient. A housing may be oriented relative to the
patient's bone, and the housing optionally defines a cavity. A
non-compressible force transmitter may be positioned within the
cavity and as a load is applied to the housing, the load can be
transmitted as a pressure to the non-compressible force
transmitter. The load profile generated by applying the load to the
housing may be monitored using a pressure sensor at least proximate
the non-compressible force transmitter. In some cases the pressure
sensor is within or adjacent the non-compressible force
transmitter.
[0019] As the load profile is generated, the load profile can be
stored. For instance, the load profile can be stored locally within
the housing or external thereto. The load profile may generally
correspond to the pressure applied by the non-compressible force
transmitter to the pressure sensor, such as when the pressure
sensor is adjacent the force transmitter. In accordance with some
aspects, the pressure sensor is substantially fully encapsulated
within the force transmitter.
[0020] As the load profile is monitored, the load profile can be
measured, stored, or otherwise monitored, or have any combination
of the foregoing performed. Monitoring the load profile can include
monitoring the load profile over a first period of time. That first
period of time may be about an hour, about a day, about a week,
about two weeks, and/or about four to six weeks. For instance, the
first period of time may correspond to a time between scheduled
visits with a physician or clinician. During such time, monitoring
of the load profile may be continuous and substantially
uninterrupted. Monitoring the load over the first period of time
may also include periodically monitoring the load for a second
period of time within the first period of time. Prior to monitoring
the load, the applied load may first be detected.
[0021] In accordance with another embodiment, a method for treating
a bone fracture patient during a period of PWB includes
substantially immobilizing the bone of the patient. A load can be
applied to a housing that defines a cavity having a flexible,
non-compressible force transmitter at least partially disposed
within the cavity. The load can then be monitored, and the load
profile can be generated by applying the load to the housing.
Monitoring may be facilitated by using a pressure sensor linked to
the force transmitter, such that the load generates a pressure
within the non-compressible force transmitter, and that force is
then transmitted to the pressure sensor.
[0022] When a pressure sensor is used to monitor the load profile,
the pressure sensor may be located at least partially within the
force transmitter or at least proximate thereto. In some
embodiments, the pressure sensor is substantially fully enclosed
within the force transmitter. In other embodiments, the pressure
sensor may be at least partially external to the force
transmitter.
[0023] As the load profile is monitored, the period of PWB can be
adjusted. Such adjustments may be based on the monitored load
profile. For instance, the period may be increased or reduced based
on the load profile. A pressure sensor used to monitor the load
profile may be calibrated. In some cases, the calibration may be
performed a single time such that monitoring the load profile is
performed without recalibration after first applying the load to
the housing.
[0024] In accordance with another example embodiment, a system for
measuring a load profile of bone fracture patient is produced.
Production of such system may include forming a housing that
defines a cavity. A non-compressible force transmitter may be
positioned at least partially within the cavity, and a pressure
sensor can be positioned at least partially within the housing. The
housing can be positioned within the footprint of a bone
immobilizer configured to substantially immobilize a bone.
[0025] The pressure sensor can be positioned to be in the
line-of-action of an applied load or pressure. In some cases, the
pressure can be applied from any direction, and the pressure sensor
can be at least partially enclosed within the force transmitter.
For instance, the force transmitter may include a silicone gel that
is optionally cured. An applied load may be transmitted through the
silicone gel as a pressure that can be monitored from any direction
or orientation within the gel. A pressure sensor can be fully
enclosed within the gel to measure the pressure. In certain
embodiments, the bone is immobilized by a lower-leg immobilizer.
The housing may be positioned within a heel region or at least
partially between a fourth and fifth metatarsal head portion of the
lower-leg immobilizer.
[0026] In one embodiment, a computer-implemented method is provided
for providing user feedback regarding compliance with a set of
partial weight bearing (PWB) criteria. A computer system receives
force data from a non-compressible force transmitter that is
assigned to a user and accesses the force data received from the
non-compressible force transmitter to determine whether the user is
within a predefined pressure compliance range. The pressure
compliance range specifies a prescribed range of pressure that is
to be applied during a PWB period. The computer system then
receives a compliance data request from the user or the user's
physician and wirelessly communicates compliance data representing
the user's compliance with the prescribed range of pressure during
the PWB period to the user and/or the user's physician.
[0027] In another embodiment, a computer system is provided that
gathers and stores force data to determine users' compliance with a
predefined pressure compliance range. The computer system receives
an indication that a period of partial weight bearing (PWB) has
been initiated for a user and initiates a non-compressible force
transmitter that is assigned to the user. The non-compressible
force transmitter is positioned both within a cavity of a housing
oriented with respect to the user's leg and adjacent to a pressure
sensor to transmit pressure within the housing. The computer system
stores, at specified intervals, force data sensed by the pressure
sensor, which indicates the user's compliance with a prescribed
range of pressure that is to be applied during the PWB period.
Then, upon receiving a request for stored force data, the computer
system sends the stored force data to the data requester.
[0028] This Summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This Summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used as an aid in determining the scope of
the claimed subject matter. Moreover, it is contemplated that each
feature identified in this Summary may be independently included
with any other one or more features identified herein, unless such
feature is expressly described as requiring use with one or more
particular other features, or by its nature cannot be used in
combination with other features herein.
[0029] Additional features and advantages will be set forth in the
description which follows, and in part will be obvious from the
description, or may be learned by the practice of the teachings
herein. Features and advantages of the present disclosure may be
realized and obtained by means of the instruments and combinations
particularly pointed out in the appended claims. Features of the
present disclosure will become more fully apparent from the
following description and appended claims, or may be learned by the
practice of the disclosed embodiments as set forth hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] To further clarify the above and other advantages and
features of the present invention, a more particular description of
the invention will be rendered by reference to specific embodiments
thereof which are illustrated in the appended drawings. It is
appreciated that these drawings depict only illustrated embodiments
of the invention and are therefore not to be considered limiting of
its scope. The invention will be described and explained with
additional specificity and detail through the use of the
accompanying drawings in which:
[0031] FIG. 1 illustrates a schematic representation of a system
for measuring an under foot profile of a patient during a period of
partial weight bearing (PWB) according to an exemplary embodiment
of the present disclosure;
[0032] FIG. 2 illustrates a cutaway perspective view of the
embodiment of the system of FIG. 1;
[0033] FIGS. 3A-3E illustrate cutaway perspective views of various
example embodiments of load profile monitoring devices usable in
connection with the systems of FIGS. 1 and 2;
[0034] FIG. 4 illustrates a perspective view of a load profile
monitoring device configured as a insole insert;
[0035] FIGS. 5A-5B illustrate cross-sectional views of various
example embodiments of load profile monitoring devices configured
as insole inserts similar to the device shown in FIG. 4;
[0036] FIG. 6 illustrates an embodiment of a method for measuring
an under foot load profile of a patient during a period of PWB;
[0037] FIG. 7 illustrates the results from one of the sensors of a
working example evaluated during pressure linearity testing;
[0038] FIG. 8 illustrates the effects of varying the diameter of
the housing of the working example on load sensor sensitivity with
a sensor height of 9 mm;
[0039] FIG. 9 illustrates the loads applied on the working example
over time during a static drift test;
[0040] FIG. 10 illustrates the average drift for an approximately
two hour period prior to, in between, and after loads were applied
to various working example systems for measuring an under foot
profile of a patient during a period of PWB;
[0041] FIG. 11 illustrates the recorded sensor output after each
set of 5,000 cycles for various working example systems for
measuring an under foot profile of a patient during a period of
PWB;
[0042] FIG. 12 illustrates a computer architecture in which
embodiments described herein may operate including providing user
feedback regarding compliance with a set of PWB criteria.
[0043] FIG. 13 illustrates a flowchart of an example method for
providing user feedback regarding compliance with a set of PWB
criteria.
[0044] FIG. 14 illustrates a flowchart of an example method for
gathering and storing force data to determine users' compliance
with a predefined pressure compliance range.
[0045] FIG. 15 illustrates an embodiment in which force data is
gathered and stored to determine users' compliance with a
predefined pressure compliance range;
[0046] FIG. 16 illustrates various alternative embodiments of a
non-compressible force transmitter;
[0047] FIG. 17 illustrates a graphical timeline of force data on a
user's heel and forefoot.
[0048] FIG. 18 illustrates an example graphical user interface
(GUI) for providing user feedback regarding compliance with a set
of PWB criteria.
DETAILED DESCRIPTION
[0049] While certain devices may be available and allow analysis of
insole pressure, gait pathology, or plantar ulcer prevention in
diabetic patients, such devices fail to provide continuous
monitoring and/or recording of the load placed on an injured limb.
Moreover, such devices are generally confined to monitoring over a
short time span, and fail to allow for continuous monitoring and/or
recording of a load over longer periods of time, such as greater
than one hour. Often, such devices may be limited in part by the
performance of their sensor technology. For example, capacitive
resistors, polymer sheet or ink based force-sensing resistors,
pneumatically coupled systems connected to a pressure sensor, or
general force-sensing resistors may suffer from limitations such as
hysteresis, creep non-linearity, poor dynamic response, temperature
effects, non-linearity, poor durability, or other limitations, or
any combination of the foregoing. Although insole pressure and/or
gait analysis devices may be useful for their intended purposes,
these systems may be limited in their ability to record the load
placed on a limb for an extended period. Furthermore, such systems
are generally very expensive.
[0050] To provide an economic solution to measuring the mechanical
environment produced by partial weight bearing (PWB), the present
application relates generally to a durable, low cost load sensor
that can record the load placed on an injured limb over an extended
period such as over a two-week or four-week period. The use of such
load sensors--including micromachined silicon piezoresistive
pressure sensors--may provide an accurate and durable load sensor
that is economic, robust, and capable of accurately measuring the
normal loads experienced by an immobilized limb. Thus, embodiments
disclosed herein or which may be learned from a practice of the
disclosure set forth herein may include systems, devices, and
methods for monitoring an under foot load profile of a patient
during a period of PWB. At least one embodiment of a system
described herein may enable clinicians to understand how PWB may be
used to direct patient outcomes, thereby potentially reducing
healing time and complications for various maladies, such as bone
fractures or other maladies.
[0051] A load profile may generally include an estimation of the
amount of weight borne by all or a portion of a patient's
lower-leg. For example, during a period of PWB, the load profile
may reflect aspects of the loading on the lower leg. The load
profile may reflect data or information such as maximum and minimum
loads placed on the lower leg, average load placed on the lower
leg, load duration, the total load over time, other aspects, or
combinations thereof.
[0052] Turning now to FIG. 1, a schematic representation is
provided for a system 100 for measuring an under foot profile of a
tibial fracture patient during a period of PWB, in accordance with
at least one exemplary embodiment of the present disclosure. While
the following description refers to a tibial fracture patient, the
present invention is not limited for use with only tibial fracture
patients. Rather, the present invention may be configured for
measuring an under foot profile of any person, regardless of
whether that person has suffered a tibial fracture, other bone
fracture, non-fracture injury, or no injury at all. Thus, while
much of the following discussion refers to tibial fractures, it
will be appreciated that such references are made merely by way of
example and not limitation.
[0053] Generally after post-fracture edema or swelling has
subsided, a tibial fracture patient may be prescribed a period of
PWB. In order to stimulate osteogenesis while minimizing mechanical
forces on the break, a PWB prescription may include the use of a
lower-leg immobilizer 102. In some embodiment, the lower-leg
immobilizer 102 may take the form of a walking boot cast, although
other types of devices may also be used. For example, any lower leg
orthosis, such as any ankle foot orthosis, a hard or other cast
boot, a camwalker, hard sole shoes, cast shoes, or a patient's
regular footwear may be used. Additionally, in some cases, a PWB
prescription may exclude the use of a lower-leg immobilizer 102
and/or may include the use of another orthotic device.
[0054] As shown in FIG. 1, a lower-leg immobilizer 102 may include
a force distribution section 104 and/or a foot bed 106. When the
lower-leg immobilizer 102 is placed on the patient's leg, the
patient's foot may be oriented with respect to, and optionally
supported upon, the foot bed 106. Accordingly, in some embodiments
the foot bed 106 may be sized, shaped, contoured, or otherwise
configured to allow a patient to comfortably support his or her
foot thereon. Further, the foot bed 106 may be oversized or
otherwise configured in some embodiments so as to accommodate feet
of different sizes, although the foot bed 106 may also be
customized for a particular patient or foot size.
[0055] The force distribution section 104 may be used to distribute
forces generated by or within the lower-leg immobilizer. For
instance, as a patient places his or her weight on the leg, the
patient's weight can generate a load that may be transferred to the
foot bed 106. Ultimately, the load may be transferred through the
force distribution section 104. Within the force distribution
section 104, one or more retention straps 108 are optionally
included. Such retention straps may facilitate distribution of the
load and/or retention or support of the patient's lower leg.
Distributing the forces generated during a period of PWB may
facilitate accelerated healing of the patient's fracture.
[0056] The lower-leg immobilizer 102 may include various features
in addition to those described herein. For example, the lower-leg
immobilizer 102 may include shock absorption features, positioning
features, traction devices, other features, or combinations
thereof. One example additional feature may include modification of
the tread 110. Rocker treads, softer materials, or other features
may improve the tread 110 for traction and/or shock absorption
aspects related to the lower-leg immobilizer 102.
[0057] FIG. 2 illustrates a cutaway, slight perspective view of an
example system for measuring an under foot profile of a tibial
fracture patient during a period of PWB, and may in some aspects be
used in connection with the system 100 of FIG. 1. Specifically,
FIG. 2 generally illustrates a foot bed 106 of a lower-leg
immobilizer 102. Although the foot bed 106 is identified as a part
of the lower-leg immobilizer 102, in instances where the PWB
prescription excludes the use of a lower-leg immobilizer 102, the
foot bed 106 may be a part of another orthotic device. For example,
another orthotic device may include a foot bed or support similar
to foot bed 106, but may exclude the force distribution section 104
(see FIG. 1) or other similar feature or section.
[0058] In order to use the lower-leg immobilizer 102 to measure,
analyze, store, or otherwise monitor a load profile of a PWB
patient, at least one load profile monitoring device 120a, 120b may
be located relative to the foot bed 106 and/or the patient.
Generally, as a user walks, peak forces are experienced at the heel
of the foot during mid-stance and at about the fourth and fifth
metatarsal heads during toe-off. Thus, in accordance with some
embodiments, and as illustrated in FIG. 2, a first load profile
monitoring device 120a may be located in the heel region 112 of the
foot bed 106 and/or a second load profile monitoring device 120b
may be located in the ball region 114 of the foot bed 106, which
ball region may be situated about in the region of the fourth and
fifth metatarsal heads. In other embodiments, a single load profile
monitoring device may be sized and/or configured to measure the
load profile in both the ball region 114 and the heel region 112,
or may be otherwise located relative to a patient's foot or the
foot bed 106. In further embodiments, more and/or fewer load
profile monitoring devices may be used in various locations of the
foot bed 106. For instance, a single load monitoring device may be
used at either the heel region 112 or in the ball region 114 of the
foot bed 106. In still other embodiments, one or more load
monitoring devices are located at other locations relative to the
foot bed.
[0059] In the illustrated embodiment, an aperture 116 is provided
for each load profile monitoring device 120a, 120b. In accordance
with some embodiments, the apertures 116 may be used as reference
apertures to facilitate obtaining of a reference pressure
measurement (e.g., atmospheric pressure). For instance, as
discussed herein, a load profile monitoring device 120a, 120b may
include a pressure sensor that utilizes an absolute or other
reference pressure to determine a relative pressure differential as
part of a load profile. The apertures 116 may thus be open and
exposed to the environment so as to have access to atmospheric
pressure. While the apertures 116 are shown as being open, one
skilled in the art will appreciate that such apertures 116 are,
however, merely exemplary. In other embodiments, for instance, one
or more protective features may be used to limit contaminants or
other materials through the apertures 116. By way of illustration,
a mesh, air-permeable foam, or other material, or any combination
of the foregoing, may be included on or within the apertures 116 to
provide protection against contaminants.
[0060] While FIG. 2 illustrates the use of apertures 116 extending
in a generally vertical direction through the foot bed 106, it
should be appreciated that such feature is merely exemplary. For
instance, in other embodiments the apertures 116 may be eliminated,
moved, or otherwise configured. In one exemplary embodiment, for
example, the apertures 116 can be eliminated and a pressure or
other aspect can be measured or otherwise monitored using a
reference pressure other than atmospheric pressure. In still other
embodiments, an absolute pressure may be used as a gauge to measure
or monitor a load profile. For instance, each load profile
monitoring device 120a, 120b may include an absolute pressure
sensor having a sensing diaphragm on one side and a sealed vacuum
cavity on an opposing side.
[0061] In accordance with some embodiments of the present
disclosure, load profile monitoring devices 120a, 120b may be
integrally formed with the foot bed 106 of the lower-leg
immobilizer 102 or other device. In other embodiments, the foot bed
106 may include a pocket and/or aperture into which the load
profile monitoring devices 120a, 120b may be selectively located
and/or fixed. Particularly in connection with embodiments in which
the load profile monitoring devices 120a, 120b are separately
formed and inserted into pockets or other structures, the load
profile monitoring devices 120a, 120b may also be selectively
removable and/or replaceable.
[0062] Turning now to FIGS. 3A-3E, various example embodiments of
load profile monitoring devices are illustrated and described in
additional detail. FIG. 3A, for instance, illustrates a cutaway
perspective view of one example embodiment of a load profile
monitoring device 120. The load profile monitoring device 120 may
include a housing 122. In some embodiments, the housing 122 of the
load profile monitoring device 120 may be inserted into a pocket
and/or aperture of a foot bed, such as foot bed 106 (see FIG. 2).
In other embodiments, the housing 122 may be integrally formed,
adjacent to, or otherwise oriented with respect to a foot bed or
other structure.
[0063] As illustrated in FIG. 3A, the housing 122 may include a
first surface 124 and a second surface 126. The first and second
surfaces 124, 126 may cooperate to define at least a portion of a
cavity 128. As shown in FIG. 3A, for instance, the first surface
124 may be an upper surface, while the second surface 126 may be a
lower surface. In some embodiments, the first surface 124 may be a
plate having interior and exterior sides. The cavity 128 can in
some embodiments be defined by interior sides of both the first and
second surfaces 124, 126 and thus be an interior cavity.
[0064] In accordance with some embodiments of the present
disclosure, the first surface 124 may be sized and/or otherwise
configured to be slidably received within the cavity 128. For
instance, the first surface 124 and the cavity 128 may, in some
embodiments, define a piston and cylinder configuration in which
the first surface 124 is movable relative to the cavity 128, the
housing 122, and/or the second surface 126. While the first surface
124 and the cavity 128 are represented as cooperating to define a
cylindrical structure, such structure is merely exemplary. In other
embodiments, the first surface 124 and the cavity 128 may be
otherwise shaped. For example, the first surface 124 and the cavity
128 may define a structure having a polygonal, spherical,
hemispherical, prismatic, or other configuration, or which has any
combination of the foregoing structures.
[0065] At least to allow some movement of the first surface 124
relative to the cavity 128 and/or the housing 122, the first
surface 124 may be flexibly connected to the second surface 126.
For example, the first surface 124 may be connected to the second
surface 126 by an elastomer, gel, other component, or a combination
thereof. The connection between the first surface 124 and the
second surface 126 may be formed by coating, bonding, integrally
forming, other connection mechanisms, or combinations thereof.
Optionally, connecting the first surface 124 with the second
surface 126 may substantially seal the cavity 128 of the housing
122 to limit and/or prevent leakage and/or passage of
contaminants.
[0066] The first surface 124 and/or the second surface 126 are
optionally formed of a rigid material. For example, the first
surface 124 and/or the second surface 126 may be formed of a rigid
urethane. Example rigid urethanes may be castable, machineable, or
can otherwise be shaped into a desired form. An example of a
suitable material is Alumilite.RTM., which is a rigid polymer that
can be cast into a desired form. Other suitable materials include
high-density polyethylene, polycarbonate, bakelite, duroplast,
acrylic plastics, polybutylene terephthalate, polyethylene
terephthalate, or any number of polymers, metals, composites,
organic materials, or other materials, or any combination of the
foregoing. In other embodiments, the first surface 124 and/or the
second surface 126 may be pliable, flexible, or semi-rigid.
[0067] In the present embodiment, the first surface 124 and the
second surface 126 are formed of the same material, and may have
the same general properties (e.g., strength, stiffness, thermal
expansion, etc.). In other embodiments, the first surface 124 and
the second surface 126 may be formed of the same or different
materials having substantially similar or different general
properties. For example, one of the first or second surfaces 124,
126 may be formed of a flexible material while the other of the
first or second surface 124, 126 may be formed of a rigid material.
In another example, the first surface 124 may be formed of a first
flexible material while the second surface 126 may be formed of a
second flexible material.
[0068] The second surface 126 of the housing 122 may include an
optional aperture 130 extending through at least a portion thereof.
The aperture 130 may correspond to the apertures 116 described
above in connection with FIG. 2, and the aperture 130 may have any
number of uses. For instance, the aperture 130 may be used to
facilitate obtaining of a reference pressure. In other embodiments,
the aperture 130 may facilitate selective removal and/or
replacement of components within the housing 122, or transmission
or communication with sensing or conditioning elements within the
load profile monitoring devices 120.
[0069] For instance, in one embodiment, the load profile monitoring
device 120 may include a pressure sensor 140. The pressure sensor
140 may be configured to measure a load profile of the patient
during a desired period of PWB, or for another treatment or
purpose. In the present embodiment, the cavity 128 may be an
interior cavity sized to receive all or a portion of the pressure
sensor 140. For instance, in this particular embodiment, the cavity
128 has a substantially uniform height that may generally
correspond to a distance between the first surface 124 and the
second surface 126. The height of the cavity 128 may be sufficient
to allow the pressure sensor 140 to be positioned therein. For
instance, in FIG. 3A, the pressure sensor 140 is wholly enclosed
within the cavity 128, although in other embodiments the pressure
sensor 140 may only be partially enclosed within the cavity 128, or
may be external to the cavity 128. In still other embodiments, the
cavity 128 may have a non-uniform height or other dimension.
[0070] The pressure sensor 140 of FIG. 3A may be in electronic
communication with any number of other components. For instance, in
this embodiment, the pressure sensor 140 is supported on a plate
146, and the plate 146 also supports a signal conditioner 142. The
plate 146 may include, for instance, a printed circuit board or
other signal communication mechanisms that can facilitate
communication between the pressure sensor 140 and the at least one
signal conditioner 142. Signal conditioners 142 may generally
include amplifiers, filters, input/output ports, microchips, other
signal conditioners, or combinations thereof.
[0071] The pressure sensor 140 may further include or be
electronically coupled to an input/output 144. The input/output 144
may be configured to receive or otherwise obtain data generated by
the pressure sensor 140. Such data may include, for instance,
profile data related to loading of the load profile monitoring
device 120, including pressures measured or otherwise monitored by
the pressure sensor 140. The input/output 144 may include or be
connected to a data acquisition or storage device and/or may be in
electronic communication with at least one power source (not
shown). A power source may include a battery power source, a direct
power source, other power sources, or combinations thereof.
[0072] The pressure sensor 140 may take any suitable form. For
instance, in at least one embodiment, the pressure sensor 140 may
include a miniature piezoresistive Wheatstone bridge sensor. A
Wheatstone bridge sensor may provide favorable mechanical
properties. By way of illustration, a Wheatstone bridge sensor may
provide high linearity, high strength, high mechanical
repeatability, high stiffness, little to no hysteresis, repeated
cycling until failure, reduced variability between other Wheatstone
bridge sensors, other features, or combinations thereof.
Furthermore, a Wheatstone bridge sensor may be capable of
monitoring loads over an extended period of time. For example, the
Wheatstone bridge sensor may be capable of monitoring loads over
about a two week period of time.
[0073] Other types of pressure sensors or other devices may also be
utilized. For instance, modified Wheatstone bridge sensors or other
types of sensors may be used. Examples of some such devices include
Carey Foster bridges, Kelvin Varley slides, Kelvin double bridges,
Maxwell bridges, Murray loop bridges, Wein's bridges, Fiber Bragg
gratings, or potentiometric, piezoelectric, electromagnetic, or
capacitive pressure sensors, transducers or manometers.
Furthermore, the manner in which pressure is measured may be varied
based on the type of pressure sensor utilized. For instance, some
pressure sensors may measure pressure relative to vacuum pressure
or atmospheric pressure, as a differential pressure in the form of
a pressure drop or gain relative to a reference pressure. For
instance, in one embodiment an absolute pressure sensor may be used
to measure a pressure relative to a vacuum within a void in the
housing 122, or a reference pressure that is pre-calibrated with
respect to the pressure sensor 140. Indeed, in some instances (see
FIG. 3B), the pressure sensor 140 may not necessarily have access
to atmospheric pressure. For instance, a pressure sensor may be
sealed within a cavity of the housing 122 and pre-calibrated to
measure pressure relative to sea level pressure or some other
pressure. Such calibration of the pressure sensor may be performed
prior to placing an initial placement of a load on the pressure
sensor, such that calibration need not be performed subsequent
beginning use of the pressure sensor in connection with a lower-leg
immobilizer or other similar device.
[0074] With respect to use of a Wheatstone bridge or other sensor
with high linearity, little to no hysteresis, reduced variability
between sensors, or other features, or combinations thereof, such
sensors may be desirable in order to reduce or eliminate the amount
of calibration required for each sensor. In general, a sensor with
high linearity, little to no hysteresis, reduced variability
between sensors, or other features or combinations thereof may
result in a more accurate sensor that may not require individual
calibration, or may not require additional calibration following an
initial calibration. Nevertheless, other sensors usable in
connection with embodiments herein may have specific and/or
repeated calibration requirements.
[0075] High strength, high mechanical repeatability (including
repeated cycling until failure), and high stiffness in a pressure
sensor may also be desirable in order to reduce and/or prevent
breakage due to stresses, fatigue, or other loading issues. For
example, pressure sensors that are subject to stresses, fatigue,
vibrational loading, or other loading issues may experience wire
breakage, damage to the device, or other problems that may affect
the accuracy of the sensor.
[0076] The particular type of pressure sensor or load profile
monitoring device used may vary in accordance with any number of
different factors. For instance, as noted previously, in some
embodiments there may be shock absorption features used in
connection with a lower-leg immobilizer that makes use of a
pressure sensor or other load profile monitoring device. In some
such cases, such shock absorption features may affect the
monitoring or degree of the load profile monitored by a load
profile monitoring device. Accordingly, a load profile monitoring
devices may be chosen to optimize use with a particular shock
absorption feature. For instance, a particular type of pressure
sensor may be less prone to the effects of a particular type of
shock absorption feature. Alternatively, another type of pressure
sensor may be adjustable so as to compensate for effects of the
shock absorption features.
[0077] Although at least one of the various mechanical or other
properties described above may be desirable, these mechanical
properties are not intended to limit the scope of the present
disclosure. Rather, the claims must be used to determine the proper
scope of the disclosure. In other words, in order to fall within
the scope of the claims a pressure sensor need not provide any of
the mechanical properties described above.
[0078] In some embodiments, the pressure sensor 140, signal
conditioner 142, plate 146, and input/output 144, or a portion
thereof, may be sealed together in an integral unit. For instance,
after securing the pressure sensor 140, signal conditioner 142,
input/output 144, or other components to the plate 146, a polymer
coating may be applied to connect such components together. Any
other suitable type of coating or shell may also be used.
[0079] As also illustrated in FIG. 3A, the pressure sensor 140 may
at least partially encapsulated by, or generally in contact with, a
force transmitter 150. In accordance with some example embodiments,
the pressure sensor 140 may directly, or indirectly via the plate
146, abut the second surface 126 of the housing 122 such that an
upper surface of the pressure sensor 140 is encapsulated by,
generally disposed within, or at least proximate, the force
transmitter 150. In another embodiment such as that depicted in
FIG. 3A, the pressure sensor 140 may be substantially fixed
relative to the housing 122. For instance, in this embodiment, the
pressure sensor 140 is supported on a plate 146 or other support
which abuts the second surface 126. A brace member 148 may also
abut or otherwise be adjacent the second surface 126. The brace
member 148 may further engage the plate 146 and/or otherwise
provide a support which maintains the plate 146 at a desired
location. For instance, where the cavity 128 has a circular
cross-sectional shape, the brace member 148 may be sized and shaped
to fit within the cavity 128, and can optionally be dimensioned to
be approximately the same size as the cavity 128. An opening, hole,
slot, or other structure can be formed in the brace member 148, and
the plate 146 can be received therein. The brace member 148 may
also be structured in other manners, or even eliminated. For
instance, an adhesive, mechanical fastener, or other device may
secure the plate 146 in a desired location. Alternatively, as
discussed hereafter, the brace member 148 and/or pressure sensor
140 may be movable within the housing 122.
[0080] In some embodiments it is nonetheless desirable to fix the
location of the plate 146 and/or the pressure sensor 140. For
instance, as shown in FIG. 3A, the pressure sensor 140 may be
exposed to atmospheric pressure via the aperture 130. The aperture
130 can align with the illustrated opening in the plate 146, as
well as with reference holes 116 (see FIG. 2). Such alignment may
allow provision of atmospheric or another pressure to the pressure
sensor 140, for use as a reference pressure. Fixing the location of
the plate 146 and/or pressure sensor 140 can facilitate maintenance
of alignment between with the aperture 130. In other embodiments,
the plate 146 and/or the pressure sensor 140 may be movable. For
instance, the reference pressure may be a gauge or relative
pressure not utilizing atmospheric pressure. Indeed, a reference
pressure may include a pressure measured by the pressure sensor 140
within the housing 122. In at least such cases, the pressure sensor
140 and/or plate 146 may be movable so as to change location,
orientation, or other configuration within the cavity 128.
[0081] The force transmitter 150 may be structured to transmit a
force received from the first surface 124, and can include any
number of different configurations, materials, or the like. For
instance, in accordance with some embodiments, the force
transmitter 150 may include a fluid or gel that may be selected to
transmit pressure from the first surface 124 and/or second surface
126 to the pressure sensor 140. Optionally, that fluid or gel may
be substantially incompressible. As a result, as a force is applied
to the force transmitter 150, the gel or fluid may experience
minimal or no compression, and may instead develop a pressure
therein, with the pressure being related to the applied load.
Alternatively, the force transmitter 150 may be some other
incompressible or substantially incompressible material, including
a solid material, biasing mechanism, or other material, or any
combination of the foregoing.
[0082] The compressibility of the force transmitter 150 may affect
the uniformity of the transmission of forces to the pressure sensor
140. However, a compressible material may be acceptable in some
situations for a force transmitter 150. For example, a minimally
compressible material may still transmit forces to the pressure
sensor 140, albeit non-uniformly in some circumstances. Examples of
an acceptable fluid or gel for a force transmitter 150 may include
a non-compressible silicone gel, other gels, other fluids, or
combinations thereof.
[0083] During manufacture of the load profile measuring device, the
force transmitter 150 may be positioned within the cavity 128.
Thereafter, a vacuum or other pressure may be applied the cavity
128. In applying a vacuum to the cavity 128, it may be possible to
remove other undesired materials (e.g., particles, gases, residues)
from within the inner cavity 128. Additionally, applying a vacuum
to cavity 128 may also provide a vacuum pressure within cavity 128
that may be used as a reference pressure for the pressure sensor
140. Application of a vacuum pressure, or other manufacturing
processes may further be used to limit or prevent later
introduction of other materials that may affect the uniformity of
compression of the force transmitter 150 or the transfer of force
from the force transmitter 150 to the pressure sensor 140.
[0084] While FIG. 3A therefore generally illustrates a load profile
monitoring device 120 in which a housing 122 includes a movable
upper surface or plate 124, and in which a non-compressible fluid
150 and pressure sensor 140 are disposed within the cavity 128, it
should be appreciated that the embodiment of FIG. 3A is merely
illustrative. For instance, although the pressure sensor 140 and/or
signal conditioner 142 are illustrated as being on a plate 146
abutting the lower, second surface 126 of the housing 122, such is
not intended as a limiting aspect of the present disclosure. For
instance, in other embodiments, the pressure sensor 140 and/or
signal conditioner 142, or a plate attached thereto, may abut the
upper, first surface 124 of the housing, may be disposed entirely
or partially within the force transmitter 150, may be oriented in a
manner that is non-parallel to the first or second surfaces 224,
226, or may be generally proximate the first or second surface 124,
126 without abutting such surfaces. Moreover, the brace member 148
may also be eliminated or modified (e.g., to allow the plate 146 to
move freely within cavity 128).
[0085] Turning now to FIG. 3B another example embodiment of a load
profile monitoring device 220 is illustrated in additional detail.
In general, the load profile monitoring device 220 is similar in
various regards to the load profile monitoring device 120 described
above with reference to FIG. 3A. Accordingly, to avoid obscuring
certain aspects of the illustrated embodiment, a full detail of all
aspects of the present embodiment may not be repeated, but may be
understood by reference to the disclosure herein.
[0086] In FIG. 3B, the load profile monitoring device 220 includes
a housing 222 in which a lower surface of an upper plate 224 and an
interior, bottom surface 226 of the housing 222 define a cavity
228. The terms upper, lower, interior, and bottom are merely
provided as relative terms based on the orientation illustrated in
FIG. 3B; however, it should be appreciated that such relative terms
are not necessarily limiting of the present disclosure as the load
profile monitoring device 220 may be oriented in any number of
different manners.
[0087] The housing 222 may define a piston and cylinder
configuration in which the upper plate 224 may be configured to be
at least partially movable relative to the cavity 228 and/or the
bottom surface 226. For instance, as a compressive force is placed
on the upper surface of the plate 224, the plate 224 may tend to
move towards the lower surface 226, which may also change a size of
the cavity 228. In some embodiments, a force transmitter 250 may
also receive a force and exert a force on the lower surface of the
plate 224, which force would tend to move the upper plate in a
direction increasing a size of the cavity 228. The force exerted by
the force transmitter 250 may be about equal and opposite that of
the compressive force applied to the upper plate. The force
transmitter 250 may, for instance, be substantially
non-compressible and thus fully or partially resist movement of the
upper plate 224 when a compressive force is applied thereto.
[0088] More particularly, the force transmitter 250 may be placed
or otherwise located within the cavity 228. The force transmitter
250 may be similar to those described elsewhere herein. Thus,
according to some embodiments, the force transmitter 250 may
include a substantially non-compressible material such as a fluid,
gel, elastomer, or the like. In still other embodiments, the force
transmitter 250 may be at least partially compressible. The force
transmitter 250 may also fill all or substantially all of the
cavity 228. As a result, when the volume of the cavity 228 is about
equal to the volume of the force transmitter 250, the force
transmitter 250 may fully or partially resist a downward, or
compressive force applied to the upper plate 224.
[0089] As the compressive force is placed on the upper surface of
the plate 224, the force may be transmitted as a pressure into the
force transmitter 250. More particularly, as noted above, the force
may compress, or attempt to compress, the force transmitter 250. As
shown in FIG. 3B, a pressure sensor 240 and signal conditioner 240
may be disposed on a plate or other support. In this embodiment,
the pressure sensor 240 may be supported in a manner that is
generally parallel to the upper plate 224 and the surface 226. As a
result, the pressure sensor 240 may also be generally in-line with
the force exerted on the force transmitter 250 by the upper plate
224. More particularly, a pressure is formed within the force
transmitter 250 as a result of the force on the upper plate 224,
and the pressure sensor 240 may monitor such pressure and any
changes thereto. The pressure sensor 240 may therefore monitor a
load profile within the housing 222 or cavity 228, and can pass
information to or through one or more of the signal conditioner 242
and an input/output 244.
[0090] In the illustrated embodiment, the lower surface 226 of the
housing 222 is shown as being substantially impermeable. Such a
construction may be contrasted with the embodiment in FIG. 3A in
which an aperture is formed in the lower surface of a housing. As
discussed previously, a pressure sensor in accordance with aspects
of the present disclosure may take any number of forms. Thus, while
an atmospheric pressure may be obtained in some embodiments (e.g.,
through an aperture exposing a pressure sensor to the environment),
in other embodiments a pressure measurement may be made in other
manners, such as by referencing a different pressure. For instance,
in the embodiment in FIG. 3B, a reference pressure may be
pre-calibrated relative to the pressure sensor 240, such that a
differential pressure relative to the reference or gauge pressure
may be monitored.
[0091] FIG. 3C illustrates still another exemplary embodiment of a
load profile monitoring device 320 in accordance with some
embodiments of the present disclosure. In the illustrated
embodiment, the load profile monitoring device 320 includes a
housing 322 defined at least partially by a first surface 324, and
a second surface 326. In this embodiment, the first surface 324
generally takes the form of an upper plate while the second surface
326 takes the form of a lower or base plate. A cavity 328 may be
defined within the housing 322, and may particularly have a size in
at least one dimension that is generally related to a distance
between the first and second surfaces 324, 326. As shown in FIG.
3C, a force transmitter 350 may be positioned at least partially
within the cavity 328.
[0092] In the illustrated embodiment, a load profile may be
monitored from within the force transmitter 350. More particularly,
in at least some embodiments, a pressure sensor 340 can be fully
encapsulated within the force transmitter 350. For instance, a
pressure sensor 340 may be supported on a support 346, and the
support plate 346 and pressure sensor 340 may be wholly internal
to, or encapsulated by the force transmitter 350. Where the force
transmitter 350 is a fluid, gel, or other similar material, the
pressure sensor 340 and force transmitter 350 optionally are able
to float or otherwise move within the force transmitter 350 to
change location and/or orientation.
[0093] As a load is placed on the first surface 324, the load can
be transferred to the force transmitter 350. In receiving the load,
a pressure related to that load can be distributed through the
force transmitter 350. The pressure sensor 340 may be in contact
with the force transmitter 350 to monitor such pressure and the
changes thereto. When the pressure sensor 340 monitors the pressure
within the force transmitter 350, the measured or other monitored
information can be provided to a signal conditioner 342 and/or an
input/output 344. In some embodiments, the signal conditioner 342
and/or the input/output 344 are fully encapsulated within the force
transmitter 350. In other embodiments, the pressure sensor 340,
support 346, signal conditioner 342, input/output 344, or any
combination of the foregoing are partially encapsulated within the
force transmitter 350.
[0094] The pressure sensor 340 may include or be electronically
coupled to the input/output 344. The input/output 344 may be
configured to receive or otherwise obtain data generated by the
pressure sensor 340, which data may include, for instance, profile
data related to loading of the load profile monitoring device 320,
including pressures measured or otherwise monitored by the pressure
sensor 340. The input/output 344 may include or be connected to a
data acquisition or storage device and/or may be in electronic
communication with at least one power source (not shown). A power
source may include a battery power source, a direct power source,
other power sources, or combinations thereof. The data acquisition
or storage device, or the power source, may be internal to the
input/output 344, or separate therefrom. For instance, in some
embodiments, the input/output 344 may be a device capable of
wireless transmission. A power source may be included in the
input/output as may a wireless transmitter. In such an embodiment,
information can be transferred wirelessly from to a data
acquisition or storage device outside the force transmitter 350
and/or the cavity 328.
[0095] FIG. 3D illustrates an embodiment of a load profile
monitoring device 420 similar to that disclosed above with respect
to FIG. 3C. For instance, a housing 422 defines a cavity 428, in
which a force transmitter 450 is located. The force transmitter 450
may be capable of transmitting a force as a pressure. By way of
illustration, a force on the housing 422 may result in a pressure
build-up within the force transmitter 450. A pressure sensor 440
may be encapsulated within the force transmitter 450 in a manner
that allows the pressure sensor 440 to measure changes to the
pressure that build-ups within the force transmitter 450.
[0096] In one embodiment, the pressure in the force transmitter 450
is omnidirectional. By way of illustration, the force transmitter
450 may include a substantially non-compressible gel. As pressure
builds-up in the gel, the pressure throughout the gel may be
substantially constant, regardless of the location or orientation
from which a measurement is made. As a result, pressure may be
monitored from any direction, and regardless of the orientation of
a pressure sensing device. Accordingly, in FIG. 3D, the load
profile monitoring device 420 may include a pressure sensor 440
and/or signal conditioner 442 which are optionally supported on a
plate or other support, and are configured to monitor pressure in a
direction that is offset from the line-of-action of the force
applied to the housing 422. By way of illustration, the load
profile monitoring device 120 of FIG. 3A may include a pressure
sensor 140 that is optionally stabilized to be oriented in a single
direction that is out of alignment with the line-of-action of an
applied force. Alternatively, the pressure sensor 140 may be
generally aligned with the line-of-action. In still other
embodiments, the pressure sensor 440 of FIG. 3D may sometimes be
offset from a line-of-action in which a force is applied to the
housing 422. For instance, the pressure sensor 440 may be free to
float, move, or otherwise change position, orientation, or other
configuration, or any combination of the foregoing, while within
the cavity 428, and even while encapsulated within the force
transmitter 450. The pressure sensor 440 may therefore monitor a
pressure even when out of alignment with a line-of-action of the
applied force. Further still, the pressure sensor 440 may receive a
pressure from the force transmitter 450 and by virtue of being
within the force transmitter 450, transmit the pressure to the
force transmitter 450.
[0097] Still another example embodiment of a load profile
monitoring device 520 is illustrated in FIG. 3E. In particular, in
the illustrated embodiment, a housing 522 includes first and second
surfaces 524, 526 which at least partially define an interior
cavity 528 of the housing 522. A force transmitter 550 is
positioned within the cavity 528.
[0098] In some embodiments, the first and second surfaces 524, 526
may be fixed relative to each other; however, in other embodiments,
one or more of the first and second surfaces 524, 526 may be
movable relative to each other. For instance, the first surface 524
could be slideably disposed relative to the housing so as to create
a piston and cylinder configuration. In the illustrated embodiment
however, the first and second surfaces 524, 526 are fixed. In this
embodiment, rather than moving all or substantially all of an upper
first surface 524 of the housing 522, an aperture 552 is formed in
the first surface 524. Positioned within the aperture 552 is a
movable element 540. The movable element 540 may be configured to
slide or otherwise move relative to the first surface 524 and/or
the second surface 526. In some embodiments, a flexible membrane
may be attached to the movable element 540 and the housing 522 to
allow the movable element 540 to move within the aperture 552 in
the first surface while also maintaining the movable element 540
flexibly secured to the housing 522.
[0099] A load may also be applied to the movable element 540. For
instance, the load profile monitoring device 520 may be used in
connection with a lower-leg immobilizer and, as the patient walks
or otherwise puts his or her weight on the immobilized foot, the
force may be exerted on the movable element 540 in the form of a
load. The movable element 540 may then exert a compressive force on
the force transmitter 550, which can optionally cause a pressure to
build within the force transmitter 550.
[0100] In at least some embodiments, the movable element 540 is a
pressure sensor, includes a pressure sensor, or is coupled to a
pressure sensor or similar device. Accordingly, in some
embodiments, the force placed on the movable element 540 may be
measured directly. In other embodiments, a pressure sensor may be
disposed within or adjacent the force transmitter 550 so as to
obtain a pressure reading when a load is placed on the movable
element 540. For instance, a pressure sensor may be disposed within
or proximate the force transmitter 550 in a manner similar to those
described above with reference to FIGS. 3A-3D. Furthermore, while
the movable element 540 may transfer a compressive force directly
to the force transmitter 550, such an embodiment is merely
exemplary. For instance, in FIG. 3E, a force distribution member
554 may be positioned between at least a portion of the movable
element 540 and the force transmitter 550. The force distribution
member 554 can have a surface area greater than that of the movable
element 540, and potentially about as large as a footprint of the
cavity 528. Thus, as the movable element 540 exerts a compressive
force on the force distribution member 554, the force distribution
member 554 can potentially move within the cavity 528, and may
further distribute the load over a larger area, thereby more
uniformly applying a pressure to the force transmitter 550.
[0101] Attention is now directed to FIG. 4, which illustrates a
load profile monitoring device 620 for use in measuring an under
foot profile of a patient during a period of PWB. As shown in FIG.
4, the load profile monitoring device 620 includes a housing 622
configured as an insole insert that may be selectively placed in
footwear worn during a period of PWB. More specifically, the
housing 622 may be sized and shaped to fit within a patient's
footwear (e.g. any ankle foot orthosis, a hard or other cast boot,
a camwalker, walking boot cast, hard sole shoe, cast shoe, or a
patient's regular footwear). As is common with insole inserts, the
insole insert configured housing 622 may be selectively placed in
or removed from the patient's footwear. Alternatively, the insole
insert configured housing 622 may be configured for permanent
placement within the patient's footwear.
[0102] The housing 622 may include a heel bed 606 and a heel ridge
607. When the housing 622 is placed in the patient's footwear, the
patient's heel may be supported upon, and optionally oriented with
respect to, the heel bed 606. Accordingly, in some embodiments the
heel bed 606 may be sized, shaped, contoured, or otherwise
configured to allow a patient to comfortably support his or her
heel thereon. The heel ridge 607 may extend around at least a
portion of the heel bed 606 to, for example, facilitate proper
positioning of the patient's heel on the heel bed 606 and/or
increase the comfort of the housing 622 when the patient's heel
rests thereon. Furthermore, the housing 622 may be oversized or
otherwise configured in some embodiments so as to accommodate more
or the entirety of the patient's foot. In other words, the housing
may be sized and shaped so that the heel bed 606 takes the form a
foot bed upon which all or a portion of the patient's foot may be
supported. Furthermore, the housing 622 may be sized to accommodate
feet of different sizes, although the housing 622 may also be
customized for a particular patient or foot size.
[0103] In order to use an insole insert configured load profile
monitoring device, such as device 620, to measure, analyze, store,
or otherwise monitor a load profile of a PWB patient, the load
profile monitoring device may include various features, structures,
or elements that perform one or more of these functions. FIGS. 5A
and 5B illustrate example embodiments of insole insert configured
load profile monitoring devices. In general, the load profile
monitoring devices of FIGS. 5A and 5B are similar in various
regards to the load profile monitoring devices described above with
reference to FIGS. 3A-3E. Accordingly, to avoid obscuring certain
aspects of the illustrated embodiment, a full detail of all aspects
of the present embodiment may not be repeated, but may be
understood by reference to the disclosure herein.
[0104] FIG. 5A, for instance, illustrates a cross-sectional view of
one example embodiment of an insole insert configured load profile
monitoring device 720. The load profile monitoring device 720 may
include a housing 722. In the illustrated embodiment, the housing
722 of the load profile monitoring device 720 is shaped and
configured as an insole insert that may be selectively or
permanently placed in a patient's footwear. The housing 722
includes a heel bed 706 and a heel ridge 707, similar to heel bed
606 and heel ridge 607 discussed above.
[0105] As illustrated in FIG. 5A, the housing 722 may include a
first surface 724 and a second surface 726. The first and second
surfaces 724, 726 may cooperate to define at least a portion of a
cavity 728. As shown in FIG. 5A, for instance, the first surface
724 may be an upper surface, while the second surface 726 may be a
lower surface. An upper plate or force distribution member 754 may
be disposed within the cavity 728 adjacent the first surface 724.
Similarly, a lower plate 746 may be disposed within the cavity 728
adjacent the second surface 726.
[0106] In accordance with some embodiments of the present
disclosure, the upper plate 754 may be sized and/or otherwise
configured to be slidably disposed within the cavity 728. For
instance, the upper plate 754 and the cavity 128 may, in some
embodiments, define a piston and cylinder configuration in which
the upper plate 754 is movable relative to the cavity 728, the
housing 722, the lower plate 746, and/or the second surface 726.
The upper plate 754 and/or the lower plate 746 may optionally be
formed of a generally rigid material. In other embodiments, the
upper plate 754 and/or the lower plate 746 may be pliable,
flexible, or semi-rigid.
[0107] In some embodiment, the upper plate 754 and the lower plate
746 are formed of the same material, and may have the same general
properties (e.g., strength, stiffness, thermal expansion, etc.). In
other embodiments, the upper plate 754 and the lower plate 746 may
be formed of the same or different materials having substantially
similar or different general properties. For example, one of the
upper or lower plates 754, 746 may be formed of a flexible material
while the other of the upper or lower plates 754, 746 may be formed
of a rigid material.
[0108] The second surface 726 of the housing 722 and/or the lower
plate 746 may include an optional aperture 730 extending
therethrough. Similar to the aperture 130 discussed above, the
aperture 730 may have any number of uses. For instance, the
aperture 730 may be used to facilitate obtaining of a reference
pressure, such as atmospheric pressure. In other embodiments, the
aperture 730 may facilitate selective removal and/or replacement of
components within the housing 722, or transmission or communication
with sensing or conditioning elements within the load profile
monitoring devices 720.
[0109] For instance, in one embodiment, the load profile monitoring
device 720 may include a pressure sensor 740. The pressure sensor
740 may be configured to measure a load profile of the patient
during a desired period of PWB, or for another treatment or
purpose. In the present embodiment, the cavity 728 may be an
interior cavity sized to receive all or a portion of the pressure
sensor 740. For instance, in this particular embodiment, the cavity
728 has a substantially uniform height that may generally
correspond to a distance between the first surface 724 and the
second surface 726. The height of the cavity 728 may be sufficient
to allow the pressure sensor 740 to be positioned therein. For
instance, in FIG. 5A, the pressure sensor 740 is wholly enclosed
within the cavity 728, although in other embodiments the pressure
sensor 740 may only be partially enclosed within the cavity 728, or
may be external to the cavity 728. In still other embodiments, the
cavity 728 may have a non-uniform height or other dimension.
[0110] The pressure sensor 740 of FIG. 5A may be in electronic
communication with any number of other components. For instance, in
this embodiment, the pressure sensor 740 is supported on lower
plate 746, and the lower plate 746 also optionally supports a
signal conditioner 742. The lower plate 146 may include, for
instance, a printed circuit board or other signal communication
mechanisms that can facilitate communication between the pressure
sensor 740 and the at least one signal conditioner 742. Signal
conditioners 742 may generally include amplifiers, filters,
input/output ports, microchips, other signal conditioners, or
combinations thereof.
[0111] Although not shown in FIG. 5A, the pressure sensor 740 may
further include or be electronically coupled to an input/output
similar to the input/output 144 discussed above. Furthermore, the
pressure sensor 740 may take any suitable form, as discussed
elsewhere herein. For instance, the pressure sensor 740 may include
a miniature piezoresistive Wheatstone bridge sensor, modified
Wheatstone bridge sensors, Carey Foster bridges, Kelvin Varley
slides, Kelvin double bridges, Maxwell bridges, Murray loop
bridges, Wein's bridges, Fiber Bragg gratings, or potentiometric,
piezoelectric, electromagnetic, or capacitive pressure sensors,
transducers or manometers.
[0112] As also discussed herein, the manner in which pressure is
measured may be varied based on the type of pressure sensor
utilized. For instance, as discussed herein, some pressure sensors
measure pressure relative to vacuum pressure or atmospheric
pressure, as a differential pressure in the form of a pressure drop
or gain relative to a reference pressure, or based on a gauge
pressure. When a sensor is used that measures pressure relative to
atmospheric pressure, the aperture 730 may be included to expose
the sensor to atmospheric pressure, thereby allowing the sensor to
use atmospheric pressure as a reference pressure.
[0113] As also illustrated in FIG. 5A, the pressure sensor 740 may
be at least partially encapsulated by, or generally in contact
with, a force transmitter 750. In accordance with some example
embodiments, the pressure sensor 740 may directly, or indirectly
via the lower plate 746, abut the second surface 726 of the housing
722 such that an upper surface of the pressure sensor 740 is
encapsulated by, generally disposed within, or at least proximate,
the force transmitter 750.
[0114] In the embodiment depicted in FIG. 5A, the pressure sensor
740 is substantially fixed relative to the housing 722. More
specifically, the pressure sensor 740 is supported on the lower
plate 746 which abuts the second surface 726. The lower plate 746
may be positioned within the cavity 728 so as to substantially
remain in a desired location. For instance, the lower plate 746 may
be sized and shaped to fit within the cavity 728, and can
optionally be dimensioned to be approximately the same size as the
cavity 728. Alternatively, a brace member, similar to brace member
148 discussed above, an adhesive, a mechanical fastener, or other
device may be used to hold the lower plate 746 in the desired
location.
[0115] In other embodiments, the lower plate 746 and/or the
pressure sensor 740 may be movable. For instance, the reference
pressure may be a gauge or relative pressure not utilizing
atmospheric pressure. Indeed, a reference pressure may include a
pressure measured by the pressure sensor 740 within the housing
722. In at least such cases, the pressure sensor 740 and/or the
lower plate 746 may be movable so as to change location,
orientation, or other configuration within the cavity 728, similar
to the embodiments shown FIGS. 3C and 3D and described above.
[0116] Like the force transmitters discussed above, the force
transmitter 750 may be structured to transmit a force received from
the first surface 724 and/or the upper plate 754, and can include
any number of different configurations, materials, or the like. For
instance, in accordance with some embodiments, the force
transmitter 750 may include a fluid or gel that may be selected to
transmit pressure from the first surface 724, upper plate 754,
lower plate 746, and/or second surface 726 to the pressure sensor
740. As a force is applied to the first surface 724 and/or the
upper plate 754, the upper plate 754 may potentially move within
the cavity 728 and, due to is relatively large surface area, may
distribute the load over a larger area, thereby more uniformly
applying a pressure to the force transmitter 750. The pressure
sensor 740 may monitor the pressure applied to the force
transmitter 750 to monitor the under foot load profile of the PWB
patient.
[0117] Turning now to FIG. 5B, another example embodiment of a load
profile monitoring device 820 is illustrated. In general, the load
profile monitoring device 820 is similar in various regards to the
load profile monitoring device 720 described above with reference
to FIG. 5A. Accordingly, to avoid obscuring certain aspects of the
illustrated embodiment, a full detail of all aspects of the present
embodiment may not be repeated, but may be understood by reference
to the disclosure herein.
[0118] In FIG. 5B, the load profile monitoring device 820 includes
a housing 822 having a heel bed 806 and a heel ridge 807. The
housing 822 also includes a first surface 824 and a second surface
826 that at least partially define a cavity 828. The first surface
824 and/or the second surface 826 may be configured to transfer a
force applied thereto to a force transmitter 850 disposed within
the cavity 828. The force transmitter 850 may be similar to those
described elsewhere herein. Thus, according to some embodiments,
the force transmitter 850 may include a substantially
non-compressible material such as a fluid, gel, elastomer, or the
like. In still other embodiments, the force transmitter 850 may be
at least partially compressible. The force transmitter 850 may also
fill all or substantially all of the cavity 828.
[0119] As the force is placed on the first surface 824 and/or the
second surface 826, the force may be transmitted as a pressure into
the force transmitter 850. More particularly, as noted above, the
force may compress, or attempt to compress, the force transmitter
850. As shown in FIG. 5B, a pressure sensor 840 and signal
conditioner 840 may be disposed on a plate 846 or other support. In
this embodiment, the pressure sensor 840 is illustrated as being
supported in a manner that is generally parallel to the first
surface 824 and the second surface 826. As a result, the pressure
sensor 840 may also be generally in-line with the force exerted on
the force transmitter 850 by the first surface 824 and/or the
second surface 826. More particularly, a pressure is formed within
the force transmitter 850 as a result of the force on the first
surface 824 and/or the second surface 826, and the pressure sensor
840 may monitor such pressure and any changes thereto. The pressure
sensor 840 may therefore monitor a load profile within the housing
822 or cavity 828, and can pass information to or through one or
more of signal conditioners 842 and an input/output (not
shown).
[0120] In the illustrated embodiment, the second surface 826 of the
housing 822 is shown as being substantially impermeable. Such a
construction may be contrasted with the embodiment in FIG. 5A in
which the aperture 730 is formed in the second surface 726 of
housing 722. As discussed previously, a pressure sensor in
accordance with aspects of the present disclosure may take any
number of forms. Thus, while an atmospheric pressure may be
obtained in some embodiments (e.g., through an aperture exposing a
pressure sensor to the environment), in other embodiments a
pressure measurement may be made in other manners, such as by
referencing a different pressure. For instance, in the embodiment
in FIG. 5B, a reference pressure may be pre-calibrated relative to
the pressure sensor 840, such that a differential pressure relative
to the reference or gauge pressure may be monitored.
[0121] In the illustrated embodiment, plate 846 is positions on or
adjacent to second surface 826, and pressure sensor 840 is
supported on plate 840. As a result, pressure sensor 840 is
positioned adjacent to, in contact with, or is disposed partially
within force transmitter 850. As discussed above in connection with
FIGS. 3C and 3D, a load profile may be monitored from within the
force transmitter 850. Thus, in at least some embodiments, the
pressure sensor 840 can be fully encapsulated within the force
transmitter 850. For instance, the pressure sensor may be supported
on a support, and the support and pressure sensor may be wholly
internal to, or encapsulated by the force transmitter, similar to
FIGS. 3C and 3D. Where the force transmitter is a fluid, gel, or
other similar material, the pressure sensor and force transmitter
optionally are able to float or otherwise move within the force
transmitter to change location and/or orientation.
[0122] As a load is placed on the first surface 824 or the second
surface 826, the load can be transferred to the force transmitter
850. In receiving the load, a pressure related to that load can be
distributed through the force transmitter 850. The pressure sensor
840 may be in contact with the force transmitter 850 to monitor
such pressure and the changes thereto. When the pressure sensor 840
monitors the pressure within the force transmitter 850, the
measured or other monitored information can be provided to the
signal conditioner 842 and/or an input/output (not shown).
[0123] As discussed above, the pressure in the force transmitter
may be omnidirectional. As a result, the build-up of pressure in
the force transmitter may be substantially constant, regardless of
the location or orientation from which a measurement is made.
Accordingly, pressure may be monitored from any direction, and
regardless of the orientation of the pressure sensing device. Thus,
the pressure sensor may be configured to monitor pressure in a
direction that is in line with or offset from the line-of-action of
the force applied to the housing, as discussed above.
[0124] FIG. 6 illustrates a method 900 for measuring an under foot
load profile of a patient during a period of PWB. In this exemplary
embodiment, the method includes substantially immobilizing a
portion of the lower leg of a patient, as indicated by act 902. The
lower leg may be immobilized by a lower-leg immobilizer including,
but not limited to, a walking boot cast or the lower-leg
immobilizer 100 described herein. As noted herein, other types of
immobilizers may be used for different bone fractures. As also
noted, some bone fractures may not require the use of an
immobilizer. Accordingly, in the method, the step of immobilizing
the lower leg may not be necessary.
[0125] The lower-leg immobilizer may include a housing, such as
housing 122, that may be oriented, as indicated by act 904, with
respect to the patient's lower leg. For example, the housing 122
may be positioned, for example, in a heel region and/or a ball
region of the patient's foot when the fractured bone is the
tibia.
[0126] A load may be applied to the load profile monitoring device,
as indicated in act 906. More particularly, a load may be applied
to an upper surface of the housing. For example, the patient may
apply a load while standing, walking, sitting, or performing other
activities. A load profile may be generated based on the applied
load on the upper surface of the housing. For instance, a pressure
sensor may be located fully or partially below the upper surface
and at least partially within the housing. This generated load
profile may be monitored, as indicated by act 908. For example, the
generated load profile may be monitored over a two-week or a
four-week period. The generated profile may be continuously
monitored without substantial interruption. Alternatively, the
generated load profile may be periodically monitored. For instance,
a pressure sensor may be configured to activate, measure, or
otherwise monitor a load only for a specified duration. The
pressure sensor may then cease monitoring the load for a time and
then again activate or otherwise monitor the load profile. Such a
process may occur over regular or irregular intervals over a full
period in which the load profile is monitored. In some embodiments,
periodic monitoring may occur at specified times or intervals. In
other embodiments, monitoring may be triggered by certain events
(e.g., detection of a load or a high load on the lower-leg
immobilizer).
[0127] The monitored load profile may be stored for later use. For
example, a data acquisition unit may be used to store the monitored
load profile. The data acquisition unit may be contained in the
housing, in the lower-leg immobilizer, or in a remote location. The
monitored load profile may be used to provide feedback to the
patient. For example, the data acquisition unit may notify the
patient when they have exceeded a prescribed PWB allowance. Direct
feedback may improve the outcomes of a patient that has been
prescribed PWB.
[0128] A user interface may be used with the monitored load
profile. For example, the peak loads (e.g., a maximum load
experienced during ambulation), an average load, or other data may
be identified and presented to the user via an interface. The load
profile information may be stored and/or used to provide direct
feedback to the patient and/or clinician.
[0129] Monitoring the load profile may be performed without
recalibration after first applying a load to the upper surface of
the housing. For example, the pressure sensor may be configured to
monitor the load profile without substantial drift.
[0130] The method 900 described above may also be used for treating
a patient during a period of PWB. For example, the load profile
data may be used to alter the initial PWB prescription. In other
words, based on characteristics of the load profile, such as peak
loads, cumulative loads, number of steps, other characteristics, or
combinations thereof, the initial PWB prescription may be altered.
In one example, for instance, a patient may have a load profile
relative to an injury, such as a fractured bone, monitored during
an extended period between check-ups. Upon detecting certain events
or loads, the time between check-ups may be altered. For instance,
upon determining that desired peak loads are being exceeded, a
patient or physician may be automatically notified that a time
between check-ups should be shortened. In contrast, if average
loads fall within a desired range, or if peak loads are less than a
set maximum, a patient or physician may be automatically notified
that a time between check-ups should be extended. Other data
related to a load profile may also be used to modify the time
between check-ups and thus also a time during which a load profile
is monitored.
WORKING EXAMPLES
[0131] An embodiment of a load sensor was configured as a piston
and cylinder design similar to that illustrated in FIG. 3A,
utilizing non-compressible silicone gel to generally uniformly
transmit the pressure inside the cylinder to a piezoresistive
Wheatstone bridge pressure sensor. In this example, the cylinder
diameter remained substantially constant and the pressure measured
by the piezoresistive sensor was converted to load.
[0132] One corner of a piezoresistive pressure sensor die (a
gauge-type microsensor -3000 series 15 psi piezoresistive pressure
sensor manufactured by Merit Sensors, Salt Lake City, USA) was
secured to a custom FR-4 printed circuit board (Circuit Graphics,
Salt Lake City, USA) using UV-cure adhesive (3311 Loctite, Henkel
Co., Dusseldorf, Germany). The piezoresistive sensor was
electrically connected to the printed circuit board by bonding
aluminum-1% silicon alloy wire (Semiconductor Packaging Materials,
Inc, Armonk, USA) between the pressure sensor die and the printed
circuit board using a 7476 D Manual Wedge bonder (West bond,
Anaheim, USA). Wire bonds were reinforced with a small amount of
acrylic-based, UV-cure adhesive (3311 Loctite). The microsensor was
further secured and sealed to the printed circuit board with a
UV-cure silicone (5248, Loctite) around the remaining base
perimeter. On the printed circuit board, the outputs of the
piezoresistive sensor were connected to an AD8220 Instrumentation
Amplifier (Analog Devices, Inc., Norword, USA) with a gain
adjusting resistor, which was soldered to the printed circuit
board. In a portion of the studies, the instrumentation amplifier
was not used, in which case the output of the piezoresistive sensor
was electrically connected directly to the output leads of the
printed circuit board. To complete the circuitry, lead-out wires
(AS 999-28-45J, Cooner Wires, Chatsworth, USA) were soldered to the
printed circuit board.
[0133] The sensor housing and upper plate were fabricated from
Alumilite.RTM. (Alumilite, Inc., Kalamazoo, USA), a two-part,
rigid, castable urethane, poured into a silicone mold and allowed
to cure for 5 minutes at room temperature. The assembled printed
circuit board was placed on the bottom of the sensor housing, and
atmospheric reference holes were provided and aligned.
Alumilite.RTM. was poured into the sensor housing to seal the
printed circuit board and leadout wires to the sensor housing.
Silbione HS firm gel LV 10-1 (Bluestar Silicones, East Brunswick,
USA) was mixed according to manufacturers specifications and
de-gassed for 30 minutes. The de-gassed gel was poured into the
sensor housing, vacuumed again, and then placed in a mechanical
convection oven for 15 minutes at 125 .degree. C. to cure the gel.
To seal the load sensor assembly, the upper plate was coated in
VST-50 silicone elastomer, placed on top of the sensor assembly,
and then placed in the oven for an additional 10 minutes to cure
the elastomer.
PRESSURE LINEARITY TESTING
[0134] Sensor sensitivity, linearity, and hysteresis were
characterized on eight load sensors by applying known air pressures
prior to and after the application of the gel, in order to assess
the effects of the non-compressible silicone gel on the performance
of the piezoresistive sensor. The eight tested load sensors were
fabricated without amplifiers on the printed circuit board. Sensors
were powered with 5V, and output voltages were recorded using a
precision datalogger (34970 A, Data Acquisition System manufactured
by Agilent Technologies, Santa Clara, USA). Pressure was applied to
the load sensor assembly with an ER3000 digital pressure controller
(Tescom, Elk River, USA). An airtight seal was created around the
top of the load sensor assembly and the pressure incremented and
decremented in 7 kPa (1 psi) steps from 0 to 210 kPa (30 psi).
After the no-gel condition was tested, 5 grams of the Silbione HS
Firm Gel was added to each load sensor and the pressure testing was
repeated.
[0135] Custom MatLab (MathWorks, Natick, USA) programs were used to
analyze data from both the 34970 A DAS and ER3000. The average
value for each pressure increment for each sensor was calculated
for both the input pressure and output voltage data. This data was
used to calculate sensitivity, linearity and hysteresis. A
Mann-Whitney U test for non-parametric data was used to determine
statistical difference between the gel and non-gel condition for
linearity.
[0136] The difference in sensitivities between the gel and no gel
conditions were virtually undetectable using the described
experimental setup. The measured sensitivity for both conditions
and all eight sensors was about 0.0015 (SD 2.3.times.10-19) V/kPa.
The average value of the correlation coefficient from the linear
fit of the output voltage versus the input pressure graph for the
no-gel and gel conditions were about 0.9998 (SD 3.5.times.10-4) and
about 0.9999 (SD 8.3.times.10-5), respectively. A Mann-Whitney
statistical test was used to compare the correlation coefficients
between the gel and no-gel condition. There was virtually zero
statistical difference between these conditions (P=0.774). FIG. 5
illustrates the results from one of the sensors evaluated during
pressure linearity testing. There was no appreciable hysteresis
between the loading and unloading curves. As there was no
appreciable difference between sensor sensitivity and hysteresis,
no further statistical analysis was performed.
SENSITIVITY BASED DIMENSION OPTIMIZATION
[0137] Nine different sensors assemblies of inner diameters of
about 20, 26, and 34 mm and heights of about 6, 9, 12 mm were
tested to evaluate the effect of the housing dimension on load
sensor sensitivity. The sensors were supplied with a 5V input
voltage (Agilent Technologies, Santa Clara, USA), and the output
voltage was read with National Instruments PCI-6221 DAQ card with a
custom Labview program (National Instruments, Austin, USA). Loading
of the sample was performed with a compression testing instrument
(model 3342--Instron, Norwood, USA). The sensor was incrementally
loaded five times in steps of 15 N from 0 to 195 N. The raw data
from the Instron and the DAQ were analyzed using Matlab and Excel.
The average voltage output from the sensor for each load was
graphed against the applied load. A linear regression was used to
calculate the sensitivity.
[0138] The sensor housing dimensions were determined to have an
effect on the sensitivity of the load sensor. The sensitivities
ranged from about 0.0014 V/N with a housing diameter of about 34 mm
to about 0.0164 V/N for a housing diameter of about 20 mm. While
the housing diameter changed the sensor sensitivity by about 0.0063
V/N, the change in housing height had a less pronounced effect with
an average change of about 0.0001 V/N. FIG. 6 displays the effects
of varying diameter on load sensor sensitivity for three sensors
with a sensor height of 9 mm.
STATIC DRIFT TESTING
[0139] The results of the sensitivity testing motivated the final
dimensions of the sensor housing in one working example, although
other suitable dimensions may be used. The inner diameter was about
26 mm, the outer diameter was about 30 mm, the thickness was about
2 mm, and the inner height was about 7.5 mm. Using these sensor
housing dimensions, six new load sensors assemblies were prepared.
The sensors were calibrated using the 3342 Instron. Input and
output voltages, were recorded about every 30 seconds with the
34970A Agilent for the total about fourteen hours of testing. Loads
of about 90N, 140N, and 180N were applied to the sensors for about
two hours with about a two hour rest period in between each load,
as shown in FIG. 7. The sensors were not rezeroed during this test
in order to assess raw drift. The output voltages from the sensors
were first normalized to the input voltage then converted to load
values in Newtons using a calibration transfer function. Full scale
drift percentage was calculated for both the return to zero and
load conditions.
[0140] The average two-hour drift at loads of about 90, 140 and
180N was about 0.52% (SD 0.04), 0.46% (SD 0.06), and 0.23% (SD
0.05), respectively of full scale output (about 500 N). The average
drift for the approximately two-hour period prior to, in between,
and after the loads were applied was about 0% (SD 0.00), 0.20% (SD
0.06), 0.23% (SD 0.07), and 0.25% (SD 0.07), respectively of full
scale output (about 500 N), as shown in FIG. 8.
CYCLIC LOADING
[0141] The load sensor was designed to function and maintain
accuracy for a minimum of 14,000 cycles, although other suitable
load sensors and/or load profile monitoring devices may be
configured for other numbers of cycles, or for continuous loading.
Four of the load sensors used for drift testing were again used for
cyclic testing. Cyclic testing was performed using a compression
test instrument (Instron Model 1331) equipped with a 10 kN load
cell and a NI SCB-68 DAQ interfaced with a custom LabView program
to record from both the sensor and the Instron simultaneously. The
Instron was programmed to cyclically load the sensors about 15,000
times from about 20-500 N at a frequency of 4 Hz. The sensors were
not rezeroed during this test in order to assess the uncorrected
effects of cyclic loading. Before the load sensors were cyclically
loaded and after each set of about 5,000 cycles, a static load of
about 400N was applied to the load sensor and the sensor output was
recorded for about 5 seconds. The calibration transfer function
used for the static drift testing was used to convert output
voltage to load. The average load recorded by the sensor after each
about 5,000 cycles was calculated by taking the mean of the entire
approximately five seconds of recording.
[0142] Cyclic testing showed varying amounts of drift between each
recording period. The average drift for all the load sensors at the
initial recording and after about 5,000, 10,000 and 15,000 cycles
was about 0 (SD 0), 7 (SD 8), 10 (SD 8), and 11 (SD 7) percent,
respectively. FIG. 9 displays the recorded sensor output after each
set of 5,000 cycles for all the sensors. Sensor 104 had the lowest
drift, reaching a maximum of about 2.0% after 15,000 cycles.
TREADMILL TEST IN A WALKING BOOT CAST
[0143] To record the normal loads experience by the tibia during
fracture recovery, the load sensor was designed to be placed in the
heel region of a lower-leg immobilizer, which is generally worn
during the entire rehabilitation period. Two subjects (one female
about 50 kg, one male about 83 kg) walked on a treadmill for 30
steps at a speed of about 1.6 km/hr wearing the lower-leg
immobilizer with the sensor placed under the heel. Two conditions
were tested. The first was without the straps of the lower-leg
immobilizer fastened. The second was with the straps securely
fastened. A new load sensor was built and calibrated prior to
testing. The load sensor's input and outputs were connected to NI
USB-6210 DAQ (National Instruments, Austin, USA) which powered the
sensor with about 5V DC and recorded the ratiometric voltage output
at about 100 Hz sampling frequency. The load sensor voltage output
was recorded for the entire duration of testing. The raw load
sensor voltage output was converted to load using a linear
calibration transfer function. Using a peak detection function in
Matlab, the maximum and minimum tibial loads were extracted from
the load profile. A paired student T-test was used to compare the
peak loads between strap and no strap condition, and a non-paired
student T-test was used to compare the peak loads between the two
subjects; P values of less than about 0.05 determined statistical
differences.
[0144] The average peak load for the male subject for the no strap
and the strap condition were about 240 N (SD 13) and about 215 N
(SD 17) respectively. The average peak load for the female subject
for the no strap and the strap condition were about 234 N (SD 15)
and about 188 (SD 14), respectively. The student T-test comparing
the no strap and strap condition for both subjects led to the
conclusion that there was a statistically significant difference
between the strap and no-strap condition (P.ltoreq.about 0.05). The
student T-test between the male and female subject for both
conditions also led to the conclusion of a statistically
significant difference between the male and female subjects in this
study (P.ltoreq.about 0.05).
PROVIDING FEEDBACK TO USERS AND PHYSICIANS
[0145] As mentioned above, lower extremity fractures are often
hindered by complications during recovery. Proper management of a
lower extremity fracture may rely on patients being able to place a
certain percentage of their weight on the limb repeatedly. In some
cases, patients are either unable to do so, or may do so in a
manner that is not in compliance with the physician's recommended
range of activity. These patients (and their physicians) may be
unaware that they are acting outside the recommend range of
activity.
[0146] FIG. 12 describes a patient feedback system 1201 that
includes various modules and other elements that provide feedback
to users and physicians. The patient feedback system may be
provided using one or more computer systems. These computer systems
may include special purpose or general-purpose computers including
computer hardware, such as, for example, one or more processors and
system memory, as discussed in greater detail below. Embodiments
described herein also include physical and other computer-readable
media for carrying or storing computer-executable instructions
and/or data structures. Such computer-readable media can be any
available media that can be accessed by a general purpose or
special purpose computer system. Computer-readable media that store
computer-executable instructions in the form of data are computer
storage media. Computer-readable media that carry
computer-executable instructions are transmission media. Thus, by
way of example, and not limitation, embodiments described herein
can comprise at least two distinctly different kinds of
computer-readable media: computer storage media and transmission
media.
[0147] Computer storage media includes RAM, ROM, EEPROM, CD-ROM,
solid state drives (SSDs) that are based on RAM, Flash memory,
phase-change memory (PCM), or other types of memory, or other
optical disk storage, magnetic disk storage or other magnetic
storage devices, or any other medium which can be used to store
desired program code means in the form of computer-executable
instructions, data or data structures and which can be accessed by
a general purpose or special purpose computer.
[0148] A "network" is defined as one or more data links and/or data
switches that enable the transport of electronic data between
computer systems and/or modules and/or other electronic devices.
When information is transferred or provided over a network (either
hardwired, wireless, or a combination of hardwired or wireless) to
a computer, the computer properly views the connection as a
transmission medium. Transmission media can include a network which
can be used to carry data or desired program code means in the form
of computer-executable instructions or in the form of data
structures and which can be accessed by a general purpose or
special purpose computer. Combinations of the above should also be
included within the scope of computer-readable media.
[0149] Further, upon reaching various computer system components,
program code means in the form of computer-executable instructions
or data structures can be transferred automatically from
transmission media to computer storage media (or vice versa). For
example, computer-executable instructions or data structures
received over a network or data link can be buffered in RAM within
a network interface module (e.g., a network interface card or
"NIC"), and then eventually transferred to computer system RAM
and/or to less volatile computer storage media at a computer
system. Thus, it should be understood that computer storage media
can be included in computer system components that also (or even
primarily) utilize transmission media.
[0150] Computer-executable (or computer-interpretable) instructions
comprise, for example, instructions which cause a general purpose
computer, special purpose computer, or special purpose processing
device to perform a certain function or group of functions. The
computer executable instructions may be, for example, binaries,
intermediate format instructions such as assembly language, or even
source code. Although the subject matter has been described in
language specific to structural features and/or methodological
acts, it is to be understood that the subject matter defined in the
appended claims is not necessarily limited to the described
features or acts described above. Rather, the described features
and acts are disclosed as example forms of implementing the
claims.
[0151] Those skilled in the art will appreciate that various
embodiments may be practiced in network computing environments with
many types of computer system configurations, including personal
computers, desktop computers, laptop computers, message processors,
hand-held devices, multi-processor systems, microprocessor-based or
programmable consumer electronics, network PCs, minicomputers,
mainframe computers, mobile telephones, PDAs, tablets, pagers,
routers, switches, and the like. Embodiments described herein may
also be practiced in distributed system environments where local
and remote computer systems that are linked (either by hardwired
data links, wireless data links, or by a combination of hardwired
and wireless data links) through a network, each perform tasks
(e.g. cloud computing, cloud services and the like). In a
distributed system environment, program modules may be located in
both local and remote memory storage devices.
[0152] In this description and the following claims, "cloud
computing" is defined as a model for enabling on-demand network
access to a shared pool of configurable computing resources (e.g.,
networks, servers, storage, applications, and services). The
definition of "cloud computing" is not limited to any of the other
numerous advantages that can be obtained from such a model when
properly deployed.
[0153] For instance, cloud computing is currently employed in the
marketplace so as to offer ubiquitous and convenient on-demand
access to the shared pool of configurable computing resources.
Furthermore, the shared pool of configurable computing resources
can be rapidly provisioned via virtualization and released with low
management effort or service provider interaction, and then scaled
accordingly.
[0154] A cloud computing model can be composed of various
characteristics such as on-demand self-service, broad network
access, resource pooling, rapid elasticity, measured service, and
so forth. A cloud computing model may also come in the form of
various service models such as, for example, Software as a Service
("SaaS"), Platform as a Service ("PaaS"), and Infrastructure as a
Service ("IaaS"). The cloud computing model may also be deployed
using different deployment models such as private cloud, community
cloud, public cloud, hybrid cloud, and so forth. In this
description and in the claims, a "cloud computing environment" is
an environment in which cloud computing is employed.
[0155] Additionally or alternatively, the functionally described
herein can be performed, at least in part, by one or more hardware
logic components. For example, and without limitation, illustrative
types of hardware logic components that can be used include
Field-programmable Gate Arrays (FPGAs), Program-specific Integrated
Circuits (ASICs), Program-specific Standard Products (ASSPs),
System-on-a-chip systems (SOCs), Complex Programmable Logic Devices
(CPLDs), and other types of programmable hardware.
[0156] Still further, system architectures described herein can
include a plurality of independent components that each contribute
to the functionality of the system as a whole. This modularity
allows for increased flexibility when approaching issues of
platform scalability and, to this end, provides a variety of
advantages. System complexity and growth can be managed more easily
through the use of smaller-scale parts with limited functional
scope. Platform fault tolerance is enhanced through the use of
these loosely coupled modules. Individual components can be grown
incrementally as business needs dictate. Modular development also
translates to decreased time to market for new functionality. New
functionality can be added or subtracted without impacting the core
system.
[0157] Thus, the patient feedback system 1201 of computing
environment 1200 may include or comprise any type of local or
distributed computing system described above. The patient feedback
system 1201 itself includes a receiving module 1202 that receives
force data 1204 from a non-compressible force transmitter 1203. The
non-compressible force transmitter may be any type of transmitter
and may be configured to transmit detected forces including
pressure. For example, the force transmitter 1203 may detect forces
applied to a leg or foot when walking or otherwise moving. As
explained above, the force transmitter may include a fluid or gel
that may be selected to transmit pressure from one surface (e.g. on
the heel of a foot brace) to a pressure sensor (1506 in FIG. 15).
Optionally, the fluid or gel may be substantially incompressible.
As a result, as a force is applied to the force transmitter 1203,
the gel or fluid may experience minimal or no compression, and may
instead develop a pressure therein, with the pressure being related
to the applied load. Alternatively, the force transmitter 1203 may
be some other incompressible or substantially incompressible
material, including a solid material, biasing mechanism, or other
material, or any combination of the foregoing.
[0158] In some embodiments, the non-compressible force transmitter
1203 may further include an accelerometer configured to monitor
limb acceleration. This limb acceleration may be correlated to limb
loading. The data may be stored with the limb loading data, and may
be processed in a similar manner The accelerometer may provide, for
example, an indication of how many footsteps the user has taken
over a certain period of time (hour, day, week, etc.). The
accelerometer may also provide an indication of the speed of the
user's footsteps. The user's speed and/or number of footsteps may
provide additional factors that can be used to determine whether a
user is acting within the physician's prescribed PWB compliance
range.
[0159] The processing module 1205 may receive the force data 1204
detected by the pressure sensor and transmitted by the force
transmitter 1203. The processing module determines whether the user
or patient (used interchangeably herein) 1209 is within a
predefined compliance range. The compliance range indicates a
recommended range of limb loading during a PWB period (i.e. a range
of weight that can be applied to the fractured limb). This
compliance range 1208 may be prescribed by a physician (doctor
1207). The compliance range may indicate a number of steps, a range
of force or load applied per step, a range of pressure per
hour/day/week or other time period. The range may be customized for
each patient. For instance, if patient 1209 has a particularly bad
fracture, the compliance range 1208 would be smaller (i.e. it would
include fewer steps, or a smaller amount of force per time period).
Alternatively, if the patient 1209 has only a slight fracture, the
compliance range may be higher. The range may also be tailored to
the patient based on his or her height, weight, body type, range of
movement, or other factors.
[0160] The processing module 1205 may access the prescribed
compliance range and compare it to the patient's compliance data
1210 as received from the non-compressible force transmitter 1203.
If the patient is outside the compliance range (either by taking
too few steps, or too many steps, or by stepping with too much
pressure), the doctor 1207 and/or the patient 1209 may be notified
using communications module 1206.
[0161] The communications module 1206 may include any type of
hardware and/or software used in wireless or wired data
transmission. In some embodiments, a wired connection may be
attached to the non-compressible force transmitter to transmit the
patient's compliance data 1210. In other embodiments, a wireless
transceiver may be placed within the non-compressible force
transmitter 1203 to transmit the patient's compliance data 1210
and/or compliance indications 1211 to various entities including
the doctor 1207, the patient 1209 and a data store 1212 that stores
the patient's medical records 1213. The data store may be local or
remote, physical or virtual, distributed or centrally located. In
some cases, transfer of all the patient's force data (to any of the
aforementioned entities) could result in excessive power
consumption, reducing battery life of the patient feedback system
1201.
[0162] Thus, at least in some embodiments, for each stride, as well
as for load maximum, values are calculated and selectively
transmitted in groups of data to the patient, physician and or data
store. Raw compliance data may be stored on a secure digital (SD)
card and may be transferred to the physician database on-demand,
when requested (e.g. during a patient's visit). Digitally
determining load values involves algorithms that search and
evaluate the stream of force data. To reduce power consumption, a
power-efficient, analog envelope and peak detection circuit may be
used, reducing the need for continuous search for characteristic
data points. The wireless data transceiver may be an embedded
transceiver embedded on an integrated microcontroller or radio
system. Moreover, to conserve power, the force transmitter may have
a sleep mode that can be regulated by activity of an accelerometer
or by determining that the force sensors have not detected loads
for a specified period of time.
[0163] In some embodiments, the non-compressible force transmitter
1203 of the patient feedback system 1201 is positioned in the heel
of a foot, ankle or leg brace. The brace may include housing
oriented with respect to the user's leg, heel or forefoot. The
housing may include a cavity for various components including the
non-compressible force transmitter 1203 and a pressure sensor that
detects pressure within the housing. Three different embodiments
are illustrated in FIG. 16. It will be understood that these are
merely three of many different embodiments for the non-compressible
force transmitter 1203. In embodiment I (1601), a piezoelectric
sensor 1604 is placed on a printed circuit board (PCB) 1605. The
printed circuit board may be surrounded by a urethane structure
1606. In embodiment II (1602), the piezoelectric sensor 1604 and
PCB 1605 may be surrounded by a silicone elastomer 1607, while in
embodiment III (1603), the piezoelectric sensor 1604, PCB 1605 and
urethane structure 1606 may all be encased in a silicone elastomer
shell 1607. Each of these embodiments provides varying levels of
structural support and protection for the piezoelectric sensor and
PCB.
[0164] The piezoelectric (pressure) sensor may be configured to
monitor limb load of a user (i.e. patient 1209) during a period of
partial weight bearing (PWB). The force data 1204 may be
transmitted by the communications module 1206 to the user, the
user's physician and/or to data store with the user's medical
records. The user's data may be encrypted before it is sent, and
the data may be sent over a secure connection established using any
of a variety of different security protocols. In some cases, the
user's data is compressed or otherwise processed to remove unwanted
or unnecessary data. This, in turn, reduces the amount of data that
is transmitted by the communications module 1206.
[0165] The raw or processed force data 1204 and/or compliance data
1210 may be displayed in a chart showing the user's movement over a
specified period of time. The graphical user interface (GUI)
generating module 1225 may generate a GUI 1226 that shows various
types of data, including compliance and force data. The GUI may
show raw data such as that shown in FIG. 17, where an amount of
pressure is tracked over time for a patient's heel and forefoot.
Additionally or alternatively, the GUI 1226 may show charts that
illustrate the user's level of compliance with the predefined
compliance range over a specified period of time.
[0166] For instance, element 1801 of FIG. 18 shows a user's current
compliance prescription (i.e. the patient is to try for a daily
number of 110 steps at 60-70% percent of their weight. Element 1802
shows that the patient had 101 steps that day that were in
compliance, 28 steps that wee above the range, and six steps that
were below the range. These steps may be graphically shown in graph
1803. Based on this information, other graphs may be generated such
as a weekly chart 1805 that shows the user's compliance data for a
week. The bars show how many steps the user took each day, and
color-coding (as described in the key 1806) indicates what the user
is to do (e.g. take fewer or more steps, or stay on track). A goal
bar 1804 may show the user where they are on a compliance scale for
the week, and may easily check to see whether they should take more
or fewer steps.
[0167] This compliance data may be dynamically incorporated into a
GUI on-demand, whenever the user (or physician) requests it. In
some cases, the patient feedback system 1201 may track the number
of times the patient views his or her movement or compliance data.
The GUI 1226 may include multiple different graphical displays
(e.g. for each time period (hour, day, week, etc., for a goal
tracker, for a current prescription indication and others)), and
may be configurable by the user or physician. The patient feedback
system 1201 may also use tracking module 1220 to track the number
of times each graphical display is viewed by the user or physician.
In some cases, the GUI may show different information for the user
and the physician. For instance, the GUI 1226 may show certain
forms of feedback throughout the PWB period, and may show the
physician a more cumulative view of the feedback data during a
follow-up appointment.
[0168] The communications module 1206 may communicate a compliance
indication 1211 as determined by the processing module 1205. The
compliance indication may indicate whether the patient is complying
with the prescribed compliance range 1208, and may also indicate
the degree of compliance (e.g. a percent over or under or an amount
of steps over or under the prescribed number, etc.). The compliance
indication 1211 sent to the physician 1207 allows the physician to
make informed decisions regarding the patient 1209. As mentioned
above, the compliance range is customizable for each user. The
compliance range may also be changed or updated as the patient
progresses through his or her recovery. The user's compliance to
any given compliance range may be determined at a specified
periodic rate, and the corresponding compliance data may likewise
be stored at that rate.
[0169] For example, the physician may indicate that compliance is
to be determined hourly, daily, weekly, or at another specified
time interval. Similarly, notifications of the user's compliance
may be transmitted at a customizable, periodic rate, or on-demand.
The specified periodic rate may be provided by the user's physician
or other medical professional. The data representing the user's
compliance with the predefined compliance range may be
automatically synchronized to the user's medical records at
specified intervals using a secure data channel. Moreover, the
physician may be automatically alerted if the user is outside of
the predefined compliance range by a specified threshold amount
(either over or under the specified compliance range).
[0170] Turning now to FIG. 13, a method 1300 is illustrated for
providing user feedback regarding compliance with a set of partial
weight bearing (PWB) criteria. The method 1300 will now be
described with frequent reference to the components and data of
environment 1200.
[0171] Method 1300 includes an act of receiving force data 1204
from a non-compressible force transmitter 1203 that is assigned to
a user 1209 (act 1310). The processing module 1205 of the patient
feedback system 1201 accesses the force data received from the
non-compressible force transmitter to determine whether the user is
within a predefined pressure compliance range 1208, where the
pressure compliance range specifies a prescribed range of pressure
that is to be applied during a PWB period (act 1320). The receiving
module 1202 receives a compliance data request 1215 from the user
1209 and/or the user's physician 1207 (act 1330). Then, in response
to the request, the communication module 1206 wirelessly (or
otherwise) communicates compliance data 1210 representing the
user's compliance with the prescribed range of pressure 1208 during
the PWB period to the user and/or the user's physician (act 1340).
This data may be stored in data store 1212 and/or used by GUI
generating module 1225 to dynamically generate a GUI 1226 for the
user or the physician. The user may then view the GUI and alter
their behavior accordingly. Similarly, the physician may view the
GUI and send an updated compliance prescription to the user
indicating an updated compliance range based on the user's
activity.
[0172] FIG. 15 generally shows such a process. In stage 1 (1501),
the patient feedback system (1201) may use sensors to determine a
patient's movements and forces (or loads) applied to their legs.
Using the patient feedback system, physicians or other users may
collect data on patient limb loading and correlate it to fracture
healing outcomes. The patient feedback system may use data driven
protocols to provide feedback to the patient and to the clinician,
as described in method 1300 above. Such an approach may not only
enable clinicians to take a more proactive approach to fracture
care and thereby reduce complications, improve outcomes and lower
costs, but also return autonomy to patients and empower them to
improve their treatment compliance and participation in their own
health care.
[0173] As outlined above, fractured bones heal more quickly when
they have an appropriate blood supply. Fractured bones also heal
more quickly when some amount of loading or pressure is applied to
the bones. This amount cannot be exceeded, however, without
stunting the desired healing. Blood supply is needed to bring the
cells, cytokines and other organic components necessary for bone
formation. Mechanical loading and strain are necessary to activate
osteogenic cells to encourage them to secrete new bone matrix.
Excessive motion of the fractured fragments or an unstable
mechanical environment at the initial stages of healing has been
shown to inhibit bone healing.
[0174] In some embodiments, a micromachined pressure sensor 1506
may be packaged in a partially constrained silicone gel and used to
continuously provide force measurements (see embodiments 1601-1603
of FIG. 16). The pressure sensor may, at least in some cases, be a
piezoresistive pressure sensor. The piezoresistive pressure sensor
may be converted into a load sensor by packaging the sensor in a
silicone gel force-transduction media enclosed within a semi-rigid
case. Since the area to which the load is applied is held constant,
the force can be calculated from the pressure measurements. The
pressure sensor in one embodiment may have desirable properties
including high linearity (correlation coefficient of 1), low static
drift (<1%) low dynamic drift (<3%), and low hysteresis, and
other qualities that bode well for long-term monitoring. Sensor
packaging can be adjusted to improve device performance As
described above, FIG. 16 displays several heel sensor designs.
Patients may be monitored when ambulating in a walking boot fitted
with the sensor.
[0175] Accordingly, at least in some cases, there may be a range of
PWB activity that will facilitate fracture healing. Extreme
variations from this range are thought to delay healing of the
fracture. This range 1208 includes the amount of weight that is to
be placed on the limb, as well as a range for the number of cycles
in which the load is to be applied to the limb needed (e.g. on a
daily/weekly basis, etc.) (e.g. prescription 1801 of FIG. 18).
Healing time and the number of complications may be reduced by
providing feedback to patients that guides them to keep their limb
loading within a prescribed range. The feedback may be provided
post-activity, or in real-time as the user is applying weight to
the limb. Thus, the prescribed range of PWB activity may include a
prescribed weight range and a prescribed number of steps.
[0176] The patient feedback system measures PWB behavior for
certain period of time (e.g. two to six weeks) and reports the data
to the patient and/or the clinician using the patient's personal
computer and/or "smart phone" over a network connection (e.g. using
a data acquisition, memory and communication module 1505 in Stage 2
(1502) of FIG. 15). The data reported to the patient will provide
feedback to the patient regarding their compliance to the PWB
prescription. The PWB monitoring data will be synched to the
patient's medical records and will notify the clinician if the
patient is dangerously out of compliance so the clinician can
intervene before complications develop (Stage 3 (1503) of FIG. 15).
The patient feedback system device design will enable incorporation
into any walking boot cast and may include one or more of the
following components: (1) a load monitoring component in the form
of an insole insert, (2) an on-board microprocessor and data
storage component to store and analyze raw data (i.e. find peak
loading), and (3) a wireless data transfer system that will
transfer data to a personal computer and/or smart phone.
[0177] Patients may be given software to install on their personal
computer or smart phone. The software downloads the data from the
patient feedback system to an online server. In some cases, the
data may also be automatically synchronized to the patient's
medical records 1213 using a secure encrypted data transfer
protocol. If the patient is dangerously out of compliance with the
prescribed PWB range, a message may be sent to the patient's
clinician. The clinician can either call the patient to discuss the
overuse of the limb, or have a scheduling team call the patient to
schedule a clinic visit to evaluate the patient for any signs of
complications and to encourage the patient to comply with the
prescribed use range (Stage 4 (1504) of FIG. 15. Software installed
on the client's computing systems and/or on the clinician's
computing systems may be configured to display the patient's limb
loading in a variety of graphical formats in GUI 1226. For
instance, the formats may include waveforms, trend plots, figural
or object displays and other displays that are able to illustrate
relationships between physiological variables.
[0178] The types of data to report to the patient may include
information regarding the magnitude and number of steps taken (see
1803 and 1805 of FIG. 18). This data can be separated into
different subsets including: number of steps that are within the
prescribed range, number of steps over the prescribed range, number
of steps below the prescribed range, and progress toward weekly or
monthly goals for the number of steps recommended (see 1802, 1804
and 1805 of FIG. 18). Color-coding can be used to warn the patients
if they have taken a dangerous number of steps outside the
prescribed range (according to key 1806). Too many steps above the
prescribed range can put the user at risk for complications. Too
few steps below the prescribed range and not enough within the
prescribed range may put the patient at risk for a delayed union.
Several graphs may be displayed on the same screen. One graph could
be a weekly histogram of the step count (1803), while another could
be a graph that shows status towards weekly step goals (1804). As
will be understood by one skilled in the art, substantially any
number of graphs may be shown in any order, and in any fashion.
[0179] Turning now to FIG. 14, a method 1400 is provided for
gathering and storing force data to determine users' compliance
with a predefined pressure compliance range. The method 1400 will
now be described with frequent reference to the components and data
of environment 1200.
[0180] Method 1400 includes an act of receiving an indication that
a period of partial weight bearing (PWB) has been initiated for
user 1209 (act 1410). In response, the patient feedback system 1201
initiates a non-compressible force transmitter 1203 that is
assigned to the user. The non-compressible force transmitter may be
positioned both within a cavity of a housing oriented with respect
to the user's leg and adjacent to a pressure sensor to transmit
pressure within the housing (act 1420). The patient feedback system
1201 may then store, at specified intervals, one or more portions
of force data 1204 sensed by the pressure sensor, where the force
data indicates the user's compliance with a prescribed range of
pressure 1208 that is to be applied during the PWB period (act
1430). Then, upon receiving a request for stored force data, the
stored force data is sent to the data requester (act 1440). Thus,
in this manner, the patient feedback system 1201 may monitor a
patient's compliance with a prescribed pressure or movement range.
That patient's compliance data may be stored and later sent to the
patient and/or the patient's physician on-demand The data may be
presented in a GUI that clearly shows how well the user is
complying with the prescribed compliance range. If the user is too
far off the compliance range, the physician may notify the patient
and may send an updated compliance range where applicable.
[0181] Accordingly, a patient feedback system is provided that
monitors a patient's use of a healing limb. The patient's
compliance data is transmitted to the patient's personal computer
or smart phone so the patient can track his or her compliance with
a prescribed range of use. The patient's compliance data is also
transmitted to a physician so the physician can monitor the
patient's compliance with the prescribed ranged of use. Still
further, the patient's compliance data may be automatically
synchronized to his or her medical records using a wireless data
transmitter.
[0182] The scope of the invention is not limited to the
aforementioned example embodiments. Moreover, a person of ordinary
skill in the art will understand that aspects of one or more of the
foregoing example embodiments may be combined with aspects of one
or more other of the foregoing examples to define yet further
embodiments within the scope of the invention. It should also be
noted that nothing herein constitutes, or should be construed as
constituting, a `critical` or `essential` element of any particular
embodiment, or group of embodiments.
[0183] The present disclosure may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes which come
within the meaning and range of equivalency of the claims are to be
embraced within their scope.
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